eindhoven university of technology master seeing things in ... · eindhoven, september 2013 seeing...

Eindhoven University of Technology

MASTER

Seeing things in a positive lightinvestigating the effects of color temperature of light on sociality and de-escalation

Heijboer, M.

Award date:2013

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https://research.tue.nl/en/studentthesis/seeing-things-in-a-positive-light(b8391456-aac3-4efd-8cdd-55ec8ba6e910).html

Eindhoven, September 2013

Seeing things in a positive lightInvestigating the effects of color temperature of light

on sociality and de-escalation

Marigo Heijboer 0589575

In partial fulfillment of the requirements for the degree of

Master of Science

in Human Technology Interaction

of the department of Industrial Engineering and Innovation Sciences

Supervisors:

Dr. Ir. Y.A.W. de Kort (Yvonne)

Dr. Ir. A. Haans (Antal)

Keywords

(Color temperature of) Light, Crowding, De-escalation, Situational cues, Social appraisal, Social behavior

Preface

The next pages will describe my graduation project at the Human Technology Interaction program of the University of Technology Eindhoven. Because of my background in Industrial Design and experience in many aspects of design projects, I really wanted to develop my own project for my graduation and combine aspects of both Industrial Design and Human Technology Interaction. Therefore I was happy that my graduation project was part of a larger project called De-Escalate, that has only recently started to investigate the potential benefits of interactive lighting in de-escalating behavior. This gave me the opportunity to determine my own direction within this project in setting-up a very exploratory study and design my own research paradigms in investigating first effects of, in this case, color temperature of light on social behavior. I enjoyed working on this awesome project and was able to integrate my interests in design and qualitative research methods and gain more insights into developing new research paradigms and techniques for evaluating novel research directions.

I would like to thank both my supervisors of the University of Technology, Eindhoven, Yvonne de Kort and Antal Haans, for their support, valuable insights and feedback in this project. Next, I would like to thank Martin Boschman, for his help with setting up the installations in the lighting lab. I would also like to thank my family and friends, for their support and help. Last but not least, I would like to thank the Awesome Office and its awesome inhabitants, for all their support and feedback and much needed fun distractions throughout the project.

Marigo HeijboerEindhoven, 17th of September, 2013

Impression of the Awesome Office

Social activities today often take place in crowded environments (e.g. urban night life). Because of the feelings of anonymity induced by crowded environments, people tend to feel less responsible for their actions and behavior becomes disinhibited and potentially aggressive. In this paper, we investigated via two different experiments whether warm white light presented in the environment can potentially act as a positive situational cue and prevent disinhibited behavior from becoming aggressive. Study 1 employed a laboratory experiment investigating whether people’s social appraisal of ambiguous social situations was affected by color temperature of light. Results of this study confirmed that people evaluated ambiguous situations in a more social way in warm white light (2900 K) compared to cold white light (5800 K). Notably, this effect was only found when the color temperature of light was changed in the room in which the situation was viewed compared to the room the participant was in, indicating the effect was potentially guided by light acting as a situational cue. Furthermore, study 2 explored real-life social interactions via an observation study. Results of this study indicated that several types of social interactions became more positive in warm white light (2700 K) compared to cold white light (5600 K). Results across studies thus indicated a positive effect of warm white light on social behavior, which could result in less anti-social and aggressive behavior. However, results were not consistent across the various measurements and more research will be required to further investigate these effects.

Abstract

Table of content1. Introduction ....................................................................................... 2. Theoretical framework ........................................................................ 2.1 Aggression ...................................................................................... 2.2 Situational cues to behavior ............................................................. 2.3 Positive situational cues .................................................................. 2.4 Light as a situational cue ................................................................. 2.4.1 Light effects on mood ............................................................... 2.4.2 Light effects on sociality ........................................................... 2.4.2.1 Atmospheric cues for situational appraisal ................................. 2.4.2.2 Sociality cues to situational appraisal ....................................... 2.4.2.3 Light effects on (social) behavior .............................................. 2.5 Research paradigm .......................................................................... 2.5.1 Experiment 1 .................................................................... 2.5.2 Experiment 2 .................................................................... 3. Study 1 – Effects of light on social appraisal ...................................... 3.1 Design ........................................................................................ 3.2 Participants ................................................................................... 3.3 Setting ........................................................................................... 3.3.1 Light manipulation ................................................................... 3.4 Measurements and tasks ................................................................ 3.4.1 Situation appraisal task ............................................................ 3.4.1.1 Measuring social appraisal ..................................................... 3.4.2 Atmosphere .......................................................................... 3.4.3 Need to belong ................................................................... 3.4.2 Mood .................................................................................. 3.5 Procedure ......................................................................................

4. Results study 1 .................................................................................. 4.1 Main analysis ........................................................................ 4.1.1 Social distance .................................................................... 4.1.2 Social valence .................................................................... 4.2 Atmospheric variables ................................................................ 4.3 Mediation analyses ....................................................................

5. Discussion study 1 ............................................................................. 5.1 The social effect of color temperature of light ................................ 5.2 Methodological paradigm ............................................................ 5.2.1 Limitations ............................................................................. 5.2.2 Novel aspects of methodology ..................................................... 5.3 Real-life effects of warm white light ..............................................

6. Study 2 Effects of light on social behavior ........................................... 6.1 Design ...................................................................................... 6.2 Observed participants ................................................................

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6.3 Setting .................................................................................... 6.3.1 Light manipulations ................................................................ 6.4 Observational measurements...................................................... 6.4.1 Observation scheme ............................................................... 6.5 Procedure ...............................................................................

7. Results study 2 ................................................................................. 7.1 Facial expression ...................................................................... 7.1.1 Arriving at the register ............................................................. 7.1.2 Paying for something .............................................................. 7.1.3 Leaving the register ................................................................ 7.2 Viewing behavior ...................................................................... 7.2.1 Interaction phases .................................................................. 7.3 Overall impression .................................................................... 7.3.1 Interaction phases .................................................................. 7.4 Communication ........................................................................ 7.4.1 Conversation ......................................................................... 7.4.2 Courtesies ...........................................................................

8. Discussion study 2 ....................................................................... 8.1 The social effect of color temperature of light .............................. 8.2 Methodological paradigm .......................................................... 8.2.1 Limitations of the observations .................................................. 8.2.2 Limitations of the light conditions .............................................. 8.2.3 Summary .............................................................................

General discussion ................................................................................

References .........................................................................................

Appendices ...........................................................................................

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Nowadays, many social activities between people take place in situations categorized by high density, or crowds. These types of situations could be crowded outdoor settings (e.g., city life, festivals, urban night life, public events) but could also be situations indoor (e.g., prisons, student dorms). When humans reside in high-density environments for longer periods of time, negative (after)effects of density can occur. For example, studies have shown that living in a high density environment can lead to decrements in health; prisoners living in high density conditions showed higher illness complaints ratings than prisoners living in low density conditions (Cox, Paulus & McCain, 1984).

Introduction

Nowadays, many social activities between people take place in situations categorized by high density, or crowds. These types of situations could be crowded outdoor settings (e.g., city life, festivals, urban night life, public events) but could also be situations indoor (e.g., prisons, student dorms). When humans reside in high-density environments for longer periods of time, negative (after)effects of density can occur. For example, studies have shown that living in a high density environment can lead to decrements in health; prisoners living in high density conditions showed higher illness complaints ratings than prisoners living in low density conditions (Cox, Paulus & McCain, 1984).

High density can also lead to immediate negative effects on humans, e.g. because people try to cope with the high density they are forced into and the loss of control this induces (Baum & Paulus, 1987; Evans & Lepore, 1992). The overall experience of coping with being inside such an environment, including one’s personal feelings towards the physical and situational conditions of the environment, is referred to as crowding and is thus different from the mere physical element of density (Baum & Paulus, 1987). This can strongly influence social behavior; e.g. attraction towards others in the environment tends to decrease (Baum & Greenberg, 1975) and less pro-social (e.g. helping) behavior (Bickman et al., 1973) is shown in crowded environments, even when crowding was only expected. Moreover, these negative effects induced by crowded environments can easily lead to escalating behavior, which could lead to situations running out of control. Escalation is defined by an ‘increase in the severity of aggressive behavior in an interpersonal conflict’ (Winstok, Eisikovits & Fishman, 2004, p283) and can be expressed in several intensities, ranging from frustration and annoyance to anger and rage. Crowded environments therefore potentially induce or increase various types of aggressive behavior.

“Positive situational cues have been seen to be beneficial in reducing aggressive behavior.”

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Nowadays, many social activities between people take place in situations categorized by high density, or crowds (see Figure 1). These types of situations could be crowded outdoor settings (e.g., city life, festivals, urban night life, public events) but could also be situations indoor (e.g., prisons, student dorms). When humans reside in high-density environments for longer periods of time, negative (after)effects of density can occur. For example, studies have shown that living in a high density environment can lead to decrements in health; prisoners living in high density conditions showed higher illness complaints ratings than prisoners living in low density conditions (Cox, Paulus & McCain, 1984).

High density can also lead to immediate negative effects on humans, e.g. because people try to cope with the high density they are forced into and the loss of control this induces (Baum & Paulus, 1987; Evans & Lepore, 1992). The overall experience of coping with being inside such an environment, including one’s personal feelings towards the physical and situational conditions of the environment, is referred to as crowding and is thus different from the mere physical element of density (Baum & Paulus, 1987). This can strongly influence social behavior; e.g. attraction towards others in the environment tends to decrease (Baum & Greenberg, 1975) and less pro-social (e.g. helping) behavior (Bickman et al., 1973) is shown in crowded environments, even when crowding was only expected. Moreover, these negative effects induced by crowded environments can easily lead to escalating behavior, which could lead to situations running out of control. Escalation is defined by an ‘increase in the severity of aggressive behavior in an interpersonal conflict’ (Winstok, Eisikovits & Fishman, 2004, p283) and can be expressed in several intensities, ranging from frustration and annoyance to anger and rage. Crowded environments therefore potentially induce or increase various types of aggressive behavior.

This study focuses on the reduction of aggressive behavior induced by crowded settings in public spaces. In order to accomplish this, it is important to investigate ways of minimizing negative effects induced by crowding and in this way prevent behavior in public spaces from escalating. We think the implementation of smart interactive lighting in such environments can offer a less expensive, less intrusive and more pleasant way of accomplishing this compared to other options available now (e.g. more police presence in public spaces). This paper begins the investigation of the potential benefits of lighting

Introduction1

Figure 1 Example of a crowd during Queens-day in Eindhoven, The Netherlands

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for de-escalating behavior by first exploring the effects of light on various aspects of social behavior. More specifically, in two experiments described in this paper the contextual effects of color temperature of light will be investigated to explore the effect of light acting as a positive situational cue and influencing social behavior. If light is seen to benefit social behavior in this way, it could potentially be beneficial in guiding social behavior in crowds and consequentially reduce aggressive behavior as well.

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Theoretical framework2The following section describes research concerning aggression and behavioral theories concerning the evocation of aggression due to crowding. Moreover, the theory of situational cues is discussed and a framework of two different pathways is described, indicating how different characteristics of light can act as beneficial situational cues.

2.1 Aggression Aggression is defined as behavior intended to hurt another person (Berkowitz, 1993; Winstok et al., 2004) and can be both verbal as well as physical. While aggression can be intentional and aimed at achieving a specific goal (proactive aggression), most aggression due to crowding is uncontrolled (impulsive aggression; Tuinier, Verhoeven & Egger, 2009). This type of aggression is most commonly induced when actions of other individuals or groups are seen as provoking, e.g. when they are regarded as frustrating, threatening, disrespectful, or injust (Potegal & Stemmler, 2010). Reactions to provocations can in turn lead to escalating behavior (Winstok et al., 2004). Both personal attitude towards escalating behavior and the capacity of acting aggressively to certain situations contribute to escalation of behavior.

Several negative elements of crowding can potentially lead to feelings of aggression and cause behavior to escalate. First, crowded environments reduce behavioral freedom/overall control and available resources, leading to various types of coping behavior including potentially aggressive behavior (Evans & Lepore, 1992; Stokols, 1972). Second, an increase in (social) arousal can reduce the desired level of privacy (Altman, 1975) and result in unwanted social interactions (Baum & Valins, 1979), which can lead to a stressful emotional state. While stress in itself is already a negative effect, it can potentially also lead to a state of anger or aggression (Donnerstein & Wilson, 1976; Kweon, Ulrich, Walker & Tassinary, 2004), thus mediating the effect of crowding on aggression. Lastly, being inside a crowd tends to increase feelings of anonymity and in turn increase social distance, essentially isolating people from each other (Hirsh, Galinsky and Zhong, 2011; Bell et al., 2001). Feeling anonymous in a crowd creates an internal deindividuated state in which individuals’ self-awareness decreases and a loss of personal identity can be detected (Zimbardo, 1970, in Diener & Wallbom, 1976). Deindividuation decreases concerns for social acceptance or evaluation of others and makes individuals less apt to monitor and regulate their own behavior. In this way, crowding can lead to an increase in disinhibited behavior that could potentially be harmful to others in the environment, e.g. when inhibitions against anti-social behavior are decreased (Diener, 1979; Hiltz, Turoff and Johnson, 1989). Diener and Wallbom (1976) showed this in their experiment; an increase in self-awareness induced by making participants view themselves in a mirror led to a decrease in cheating behavior (in this case, cheating behavior was described as performing a task longer than allowed) compared to when this self-awareness priming was not present.

Overall, when anonymity increases and self-awareness decreases, individuals are more guided by situational cues to regulate behavior (Hirsh et al., 2011) and conform more easily to group behavior (Hiltz et al., 1989; Lea & Spears, 1991) instead of personal norms. The next part of this literature overview will focus on this aspect of crowding and discuss ways of counteracting this effect.

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2.2 Situational cues to behavior

Disinhibition is often regarded as leading to negative behavior, but in reality it leads to a ‘passive’ behavioral state. While sometimes people become more rude, violent or aggressive after disinhibition has occurred (toxic disinhibition), people can also become more open, generous and show an increase in pro-social behavior (benign disinhibition; Suler, 2004). For example, an induced feeling of anonymity can lead to an increase in cheating behavior when this is exhibited as an option offering greater reward (Zhong et al., 2010), but it can also help people to express awkward but helpful things to strangers, e.g. an open zipper (Bohns et al., 2010, in Hirsh et al., 2011). The behavior that is presented when in a state of disinhibition is dependent on both dispositional factors (e.g. whether individuals are easily triggered into an aggressive state) and situational factors (e.g. Hirsh et al., 2011). However, when in a state of disinhibition, people tend to follow the most prominent option available to them and ignore other options. For example, Johnson and Downing (1979) showed that when participants were unidentifiable (thus, anonymous), intensity of shocks given to others increased when a negative situational cue was presented (participants dressed in clothes from the Ku Klux Klan), but decreased when a positive cue was presented (participants dressed in nurses’ uniforms). Since participants’ concern about the evaluation of their actions was reduced, situational effects, whether pro-social or anti-social, guided behavior in this case. This study indicates that both personal and contextual variables play an important role in guiding behavior in people, especially when they were made to feel anonymous.

Most actions taken against de-escalating behavior in the Netherlands today involve professionals intervening in potentially escalating situations such as having more policemen present, but also include enforcing house-rules created by clubs or offering awareness about alcohol abuse to young people (Muller et al., 2011, p164). Although the police can intervene when situations do escalate and prevent further harm, they can also serve as aggressive situational cues themselves (Reicher, 1996). Especially when individuals are in a state of disinhibition, the cues evoked by weapons and police can induce negative emotions and aggressive behavior as is explained by the ‘weapons effect’ (Berkowitz & LePage, 1967; Carlson, Marcues-Newhall & Millar, 1990). Carlson et al. (1990) propose three ways in which these cues could induce aggression, based on the work of Berkowitz (e.g. Berkowitz, 1974). First, when people have previously associated these cues with some form of aggression, viewing the cues again can evoke conditioned aggressive responses. Second, situational cues that are linked to images of violence in one’s mind could facilitate negative emotions such as stress and consequentially the expression of aggression. Third, viewing such cues might make people that aggressive behavior is warranted. Although the ‘weapons effect’ has been challenged by some researchers, Carlson et al. (1990) did find evidence that aggression-related cues presented to participants increased aggressive behavior, and that these effects were strongest when participants were negatively aroused prior to exposure.

2.3 Positive situational cues

Changes in the environment can also increase positive feelings and a positive atmosphere, leading to an increase in pro-social behavior instead. Ulrich (1991) proposes that three guidelines could be followed for creating a so-called supportive environment aimed at reducing stress. Environments should offer people a sense of control, for example by offering guidance in getting out of certain situations. Second, environments should offer social support, e.g. by allowing for social interaction and creating a bond between people in the environment. This feeling of support can help people face stressful situations (Moos & Holahan, 2003). Last, offering positive distractions in the environment that could elicit positive feelings and shed a positive light on the environment can reduce

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stress. This is related to the concept of affective cues (“sensory objects in the situation that may elicit affective responses or meaning”; Blascovich & Mendes, 2000, p70). Ulrich states that the most effective positive distractions (or positive affective cues) include happy/caring faces, animals and nature elements such as trees and water. However, other potential elements of an environment could also offer a positive cue. For example, in a recent study, Krahé and Bieneck (2012) showed that offering pleasant music to participants as a situational cue increased participants’ positive mood. Moreover, the pleasant music reduced feelings of anger and aggressive behavior in response to an aggressive cue (provocation via negative feedback on a prior task). This indicates that pleasant music can potentially decrease aggressive behavior by acting as a positive cue in the environment. Another important environmental factor that could act as a powerful situational cue is light. Employing various types of lighting in an environment has been shown to impact the atmosphere and appraisal of the environment (Baron, Rea & Daniels, 1992; Bronckers, 2009; Custers, de Kort, IJsselsteijn & de Kruiff, 2010; Flynn, Spencer, Martyniuk & Hendrick, 1973; Manav, 2007; Veitch, Newsham, Boyce & Jones, 2008; Vogels, 2008). Moreover, several studies have indicated positive effects lighting can induce; bright light has been shown to help people who suffer from seasonal depression disorder (Rosenthal et al., 1985), pulsating light has been proven to reduce anxiety (Horst, 2012); and warm white light settings increase positive social behavior (Baron et al., 1992). Moreover, Wan (2011) found that people who were presented with orange colored lighting rated the lighting to be more of a positive distracter than people in white pulsating light did, indicating specific characteristics of lighting can act as positive distracters in the environment. Since lighting can be easily adjusted and implemented in various environments at low costs, it is worth exploring in what way lighting could be beneficial in offering positive cues.

2.4 Light as a situational cue

Cues offered by various light settings could be beneficial for guiding people’s social appraisal of the situation in two ways. First, various characteristics of light (e.g. illumination, color, color temperature of light) could potentially affect people’s mood, possibly as a result of people’s personal preference (Veitch et al., 2008). When in a more positive mood, people tend to act more positively as well (Baron & Rea, 1991), which could lead to more positive social behavior (pathway 1, see Figure 2).Second, light could act as a (positive or negative) situational cue in the environment, similar to music (Krahé & Bieneck, 2012). By inducing a positive situational cue via the light settings in an environment, people’s social appraisal of the situation in these environments might be guided in a positive way as well (pathway 2). This effect could potentially be influenced by the effect of light on people’s impression of the atmosphere in the environment (pathway 3). This could in turn lead to a potential change in people’s own behavior towards others inside these environments as well.This section describes existing research on various characteristics of light explaining these two different pathways (see Figure 2 for a visual overview).

Figure 2 Visual representation of the pathways

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Various perceptual characteristics of light have been seen to affect people’s mood, atmospheric perception and/or behavior. These include the intensity of a light source (I); a measure of the illumination of the light source (lux) (Mather, 2009), the color of light (C); described in hue, saturation and brightness (Mather, 2009) and the color temperature of the light (CCT); a measure for the color of white light in Kelvin (K) (Bronckers, 2009). Low color temperatures (2700-3000 K) are considered warm colors (e.g. warm white light) and look reddish or yellowish. High color temperatures (5000 K and more) are considered cold colors (e.g. cold white light) and look bluish. Color temperatures of around 3000-4000 are considered neutral.

2.4.1 Light effects on moodThe first pathway is based on the fact that various characteristics of light can affect people’s mood, which in turn could lead to more positive evaluations and behavior in social situations. Several studies have shown that various characteristics of light directly influence people’s mood. Knez (1995) found a link between illuminance and color temperature of light; under high illuminances (1500 lux) people’s mood was more positive in warm white light than in cold white light, while under “low” illuminances (300 lux) the opposite was true. However, these results are contradicted by Baron et al. (1992) who state that people reported feeling more calm and less tense in warm white light under “low” illuminance (150 lux) than under high illuminance (1500 lux). Similar results were found by McCloughan, Aspinall and Webb (1996); participants in their study felt more positive under “low” illuminances (300-320 lux) than under “high” illuminances (730-750 lux).

The latter results might be influenced by people’s preference for certain light settings. The warm white light of low illuminance is most similar to lighting in most homes and restaurants, which could explain why people prefer this type of light setting. This in turn might lead people to feel more at ease and more positive in these environments. Indeed, the link between people’s appraisal and preference for certain environments was demonstrated by Veitch et al. (2008). In their study, they investigated the mechanisms behind the influence of various light settings in an office on task performance and well-being. Results of this study showed that people who rated the office lighting more positively also found the environment to be more attractive, which led to a more pleasurable overall mood state. This indicates that preferences people hold for certain light settings might indirectly influence their mood while in these environments.

Most research investigating people’s preferences towards various light settings has indicated that higher illuminance is generally preferred to lower illuminance (Bronckers, 2009; Manav, 2007). However, this preference may be highly dependent on the situation a person is in. For example, lower iluminance light (e.g. dim lighting) is also regarded as more intimate (Carr & Dabbs, 1974) and might be preferred in situations that require a high level of intimacy. Moreover, the range from low illuminance to high illuminance differs between studies and sometimes “low” illuminance is comparable to lighting in offices (e.g. 300 lux as used by Knez, 1995). This could explain some of the discrepancies between the mood states found in the studies of Knez (1995) and Baron et al. (1992).

Regarding color temperature of light, warm white light is generally preferred over cold white light (van Erp, 2008, in Bronckers, 2009) and environments lit with warm white light are rated more positively and are more preferred for relaxation than environments lit by cold white light (Baron et al., 1992; Manav, 2007). These types of light settings might thus also influence people’s mood state comparably. McCloughan et al. (1996) offer some initial indications of this. In their experiment, participants’ mood when exposed to lower color temperatures (3000 K) became more positive during exposure time than participant’s mood in “higher” or neutral color temperatures (4000 K).

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Studies have also been conducted investigating the effects of various colored lighting on preference. In her study, Limpens (2012) investigated associations of participants with different colored light setting. She found that participants associated orange pulsating lighting with calmness significantly more than yellow pulsating light. Moreover, yellow pulsating light was more strongly associated with threat than both orange and magenta pulsating light. Bronckers (2009) has also investigated people’s preference for different colored light, and found that cyan and yellow were most preferred. These results seem to contradict each other somewhat (e.g. while yellow is preferred more, it is also related more to threat). However, it is important to note that the preference for the hue of color depends highly on personal experiences (Ou, Luo, Woodcock & Wright, 2003). This preference may be more pronounced in environments lit by different colors of light compared to environments lit by different color temperatures of light.

Although these studies sometimes contradict each other in their relationship between light settings and preference, most studies find similar results when comparing warm and cold white light. Warm white light is mostly preferred and induces more positive feelings than cold white light does (Baron et al., 1992; van Erp, 2008, in Bronckers, 2009; Manav, 2007). Color temperature of light can thus potentially guide people’s affective evaluations of an environment and in turn affect their mood. There is however an exception to this; in a follow-up study, Knez (1995) found that while females felt most negative in cold white light compared to warm white light, males showed an opposite pattern. This indicates that males and females might have emotionally different reactions to color temperature of light.

2.4.2 Light effects on socialityThe second pathway, which is of most interest for the current project, is the effect of light on sociality, e.g. social appraisal and social behavior. Several characteristics of light could affect people’s social appraisal of various environments, leading to a change in the social appraisal of events taking place in these environments. In turn, because of a change in people’s social appraisal of situations, several characteristics of light could also influence people’s social behavior in these situations. The effect of the various characteristics of light on the social appraisal of various situations could be guided by the difference in atmospheric impressions induced by these different types of light. However, the effect could also be more direct, possibly guided by the social aspects of warmth linked to warm white light.

2.4.2.1 Atmospheric cues for situational appraisalIn order to establish a measure for the affective evaluation of environments as opposed to a person’s internal affective state, Vogels (2008) established a tool aimed to measure the atmosphere of an environment. This is based on four atmospheric dimensions; coziness, liveliness, tenseness and detachment. Within this distinction, coziness and liveliness can be seen as describing a more socially pleasing environment, while tenseness and detachment describe a more socially displeasing environment. Several characteristics of light affect these atmospheric variables in different ways, which will be explained in the following paragraphs.

Custers et al., (2010) explored how various aspects of illumination (brightness, contrast and glare and spark) affected people’s appraisal of the environment. Their results indicated that brightness significantly increases perceived tenseness and detachment, and decreases coziness. Contrast was seen to significantly decrease perceived tenseness however, and glare and spark significantly decreased detachment, and increased liveliness.

Various types of colored light (mostly distinguished by hue) have also been shown to

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impact atmospheric variables in the environment. Bronckers (2009) showed that an environment with red colored light, compared to magenta, blue, cyan, green and white, was seen as the most cozy and least detached, but also most tense. Environments containing blue and white light appeared least cozy. Other studies have found comparable results, with people evaluating atmospheres in red colored light as more cozy, more lively and less detached but also more tense compared to a range of other hues, including blue and white (Bronckers, 2009; Moors, 2009, in Bronckers, 2009).

Research studying the effect of color of light temperature on separate atmospheric variables offers different results across studies. While Bronckers (2009) found that environments with warm white light were perceived as more cozy, but also more tense and detached than cold white light, others (e.g. Moors, 2009, in Bronkers, 2009; van Erp, 2008, in Bronkers, 2009) found warm white light (reddish appearance) was perceived as more cozy, less tense and less detached than cold white light (bluish appearance). Bronckers (2009) suggested that this might be due to experimental paradigms of the studies; while Bronckers (2009) used a between-subjects design, the other two researchers employed a within-subjects design. Being able to compare both white light conditions might lead to different evaluations of the environmental lighting, perhaps because adaptation is less likely to occur.

Overall, these studies indicate that illumination, color and color temperature of light could potentially affect people’s appraisal of the atmosphere of the environment. More specifically, most studies agree that both red colored and warm white light lead to a more social evaluation of environments (via an increase in coziness) compared to blue colored and cold white light (via an increase in detachment). In turn, this could lead to a difference in social appraisal of the situations taking place in these environments.

2.4.2.2 Sociality cues to situational appraisalBesides potentially guiding people’s social appraisal of situations via the atmospheric impression induced by light, various characteristics of light could also affect the social appraisal of situations via other mechanisms.

Although not much research has been done to investigate these mechanisms, research investigating warmth and sociality can offer some clues of the possible social aspect of color temperature of light. Research in this field has shown that when people are cued with a sense of warmth, e.g. by holding a warm beverage for a short while before an experiment, they rated other persons as warmer (e.g. personal traits related to warmth scored significantly higher), were more likely to offer gifts to a friend and felt closer to another person (IJzerman & Semin, 2009; Williams & Bargh, 2008). Physical warmth thus is seen to induce a social cue for the relationships between people. Since high color temperatures (cold white light) are regarded as “cold” compared to low color temperatures (warm white light) which are regarded as “warm” (Van Erp, 2008, in Bronckers, 2009), color temperature of light might have the same effects on social behavior as physical warmth does. Indeed, the study by Baron, Rea and Daniels (1992) indicated that participants evaluated a fictive person more positively in warm white light. This shows that color temperature of light can influence social feelings towards others. However, the effect of atmosphere was not investigated in this study.

Colored light has also been shown to induce comparable feelings of sociality. In a study investigating people’s judgment about the degree of emotional expression present in different conversations, Takahashi (2009) found that participants placed in a room with red colored light judged conversations to contain more emotional expressions compared to participants in a room with white colored lighting. Moreover, they found that blue colored lighting seemed to inhibit participants’ emotional responses. Red colored light is thus seen to be linked to sociality and allows people to evaluate situations more socially.

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These effects were however only found for conversations that contained no emotional cues; when conversations were less ambiguous (e.g. containing other judgment cues such as emotionally expressive words), the effect disappeared. Moreover, no underlying mechanisms were explored in this experiment, so it is not clear whether the effect of colored light is guided by other aspects.

These results indicate that both red colored light and warm white light might increase feelings of sociality towards the environment and the people in it by acting as a social situational cue, possibly mediated by other aspects such as the perceived temperature of the light.

2.4.2.3 Light effects on (social) behaviorNext to, or perhaps as a result of, the effects of various characteristics of light on people’s situational appraisal, light has also been shown to influence various aspects of actual (social) behavior inside an environment. Research has shown that employing various characteristics of light (e.g. illumination, color or color temperature) not only influences the evaluation of the environments, but can affect people’s behavior inside this environment as well.

Darkness and dim light settings can induce a sense of perceived anonymity leading to either dishonest (Zhong et al., 2010) and aggressive behavior (Page and Moss, 1976), or, on the other hand, to more cooperative (Werth, Steidle & Hanke, 2012) and social behavior (Gergen, Gergen & Barton, 1973). These effects are highly dependent on the situation in which they are assessed (Gergen, Gergen & Barton, 1973) and might be induced via different mechanisms. Examples of these included the evolutionary perspective of black and darkness as evil, compared to white and light (Lakens, Semin & Foroni, 2011) and fear of the dark, related to the invisibility of danger in the dark (Wennekers, Holland, Wigboldus & Van Knippenberg, 2012).

Less research has been done investigating behavior in different colored light or in different color temperatures of light. In her master thesis, Dijkstra (2010) investigated the effects of colored light on creativity. Although results were inconclusive, blue colored light did seem to induce more creativity than white light in the room. However, Dijkstra (2010) was unable to replicate the findings of Metha and Zhu (2009), who found that the color blue induces more creativity than the color red. This might have been due to the fact that the light conditions in her study were introduced in the general lighting of the room, but not directly linked to the tasks in the experiment, while the colors in the experiments of Metha and Zhu (2009) were presented in the background of each task (on the screen or on paper).

Also, some research has shown that color temperature of light can influence attitudes and behavior; in warm white light, people show stronger preferences for resolving conflicts through collaboration and show an increase in donation of time and money (Baron et al., 1992; Baron & Rea, 1991; Van ‘t Sant, 2012).

2.5 Research paradigm

To summarize, research has shown that various characteristics of light can indeed influence people’s social appraisal and behavior of and in environments. Although research on both color and color temperature of light has focused mostly on the positive effects of red colored and warm white light, colored light is expected to be more affected by personal preferences (Ou et al., 2003). For this reason, color temperature of light is seen as the most interesting lighting attribute in the context of our research into de-escalating measurements.

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Inserting warm white light into an environment could possibly induce more pro-social behavior and perhaps even reduce aggressive behavior. However, it is difficult to test specific benefits of warm white light in crowded environments, especially with respect to aggression, because of a lot of confounding situational cues that could play a role, the complexity of assessing behavior in crowds and ethical concerns with regards to inducing aggression. For this reason, this paper will describe two studies exploring the effects of color temperature of light on social appraisal and social behavior in various settings.

2.5.1 Experiment 1The first study is aimed at contributing to other lighting research (e.g. Baron and Rea, 1991; Baron et al., 1992; ‘t Sant, 2012) and will employ a laboratory experiment investigating the potential benefits of warm white light in guiding a more social appraisal of ambiguous situations and the people therein, and whether warm white light leads to stronger feelings of sociality, by acting as a situational cue. More precisely, this experiment will investigate the following:

If warm white light can induce higher levels of sociality, this could benefit the reduction of aggression as well, since people would feel more positive towards one another.

In this study we were also interested in exploring whether this effect was directed by light acting as a situational cue (pathways 2 and 3 as explained in Figure 1) compared to light affecting people’s mood state (pathway 1). When the evaluated situation is coupled with the color temperature of light, people might be more likely to use the light setting in the environment to interpret other aspects in the environment, e.g. people or behavior. To explore this, the placement of the induced light settings was manipulated as well and the following was investigated:

2.5.2 Experiment 2Because we eventually hope to change people’s actual behavior inside (crowded) environments, a second study was also employed to investigate the effect of color temperature of light on real-life behavior. In this study we observed people’s interactions in a real-life setting, a cafeteria, in warm and cold white light More specifically, in this second study we were interested in the following:

This paper will describe both exploratory studies in order to shed more light on the influence of color temperature of light on social appraisal and social behavior, in order to investigate the benefits of color temperature of light on inducing more positive approaches and behavior towards social situations.

“What is the effect of color temperature of light (warm vs. cold) on the social appraisal of an ambiguous situation?”

“Is the effect of color temperature of light guided by a coupling between the light and the self, or between the light and the situation?”

“What is the effect of color temperature of light (warm vs. cold) on the sociality of people’s interaction towards the cashier when paying food at a register?”

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Study 1 Effects of light on social appraisal3This section will describe the set-up of the first experiment that focused on the investigation of the effects of color temperature of light on the social appraisal of various situations. In the experiment, participants were asked to evaluate various ambiguous social situations in different light conditions (cold vs. warm white light). Based on some earlier research regarding color temperature of light (Baron et al., 1992; van ‘t Sant, 2012) and placement of light (Dijkstra, 2010), two hypotheses were formulated for this experiment. Firstly we hypothesized that, 1) when an ambiguous situation is viewed in warm white light, this situation and the persons therein will be evaluated more positively and in a more social way compared to when the situation is viewed in a cold white light. Secondly, we hypothesized that 2) this effect will be guided by light acting as a situational cue and will thus be visible when the situation is coupled with the color temperature of light, but not when it is coupled with the environment the evaluator him/herself is in. Last, although we did not specifically hypothesize an effect, atmosphere perception in both light conditions was also measured in order to possibly offer more insights into the effect of color temperature of light, if such an effect would be found.

3.1 Design

In the experiment, participants were presented with 2D pictures portraying ambiguous social situations. Participants were asked to explain these situations. The effect of light was measured according to a mixed experimental design. The effect of placement of light (illuminating the situation itself (situation light placement) or illuminating the person (participant light placement) was included as a between-subject variable. The effect of color temperature of light (warm, 2900 K vs. cold, 5800 K) was included as a within-subject variable and was alternated for each picture.

3.2 Participants

Participants were mostly students recruited via the JFS participant database of Human-Technology Interaction (Eindhoven University of Technology) and via word-of-mouth. In total, 64 participants took part in the experiment (30 females and 34 males; mean age = 22.4 years, SD = 3.08, range 18 to 33). Participants received an incentive of €5 (€7 for participants from outside the University and Fontys Hogeschool) for their effort.

3.3 Setting

The experiment was conducted in the Lightinglab of the Eindhoven University of Technology. The walls and the ceiling in this room were off-white with a reflectance of 88% and 96.2 % respectively. The floor was dark grey with a reflectance of 5 %. The room was divided in two separate parts. The participant was seated at a desk in one part of the room and answered the questionnaires here (participant room). Apart from this desk, a chair and small cabinet, not other objects were present in this part of the room. The pictures portraying the situations were printed on A1 paper (841 mm wide, 594 mm high) and visible in the other part of the room through a window in the dividing wall (situation room). Participants were seated approximately 3.6 meters from the picture (and 1.8 meters from the dividing wall). Figure 3 shows an impression of the visual appearance of the room as viewed from the participant’s perspective.

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Figure 3 Viewpoint of experiment from participant’s perspective; right shows a situation viewed in warm white light (induced in the situation room), right shows the same situation viewed in cold white light.

3.3.1 Light manipulationIn the Lightinglab, 30 DALI controllable Philips Savio ceiling fixtures are installed which were used for this study. A DMXServerW was used to communicate with the lighting fixtures and to set the illumination and correlated color temperature of each lighting fixture. The light conditions employed in the experiment consisted of two variables; the placement of light (situation or participant light placement) and the color temperature of light (warm or cold). The placement of light was held constant within each experiment and counterbalanced between participants. The color temperature of light was changed manually together with the changing of the situation to be evaluated using the DualSelector application. The color temperature of light thus changed from warm to cold (or opposite) several times during the experiment in one of the experimental areas, while the color temperature in the other area was constantly neutral. Figure 4 shows the different light conditions that could occur.

Figure 4 Overview of different light conditions; the left picture shows the warm and cold white light in the situation condition, the right picture shows the same light in the participant condition

These light manipulations resulted in a warm white light condition (2900 K), a cold white light condition (5800 K) and a neutral light condition (4000 K). In all light conditions, the light intensity was approximately 200 lux, measured at eye-level of the participant. Table 1 shows an overview of the measurements taken in each specific lighting condition. A complete overview can be found in Appendix A.

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3.4 Measurements and tasks

For the main task, participants were asked to evaluate several social situations presented to them. Participants were also asked to fill in several questionnaires to determine whether our results could be explained via other variables. These included a mood measurement, a measurement for atmospheric perception of the room and measurements exploring participant’s need for sociality. All the questionnaires were filled out in a physical booklet designed for the experiment (see Appendix B).

3.4.1 Situation appraisal taskTo investigate participants’ appraisal of various social situations, we presented them with eight pictures of ambiguous social situations. Participants were instructed to “write down in three sentences what you think is happening in the picture and how the depicted persons are feeling”. This method was based on the Thematic Apperception Test, which was originally introduced by Christina Morgan and Henry Murray in 1935 (Vane, 1981). The test was originally meant to “analyze the unconscious fantasies of the test taker by means of evaluating the stories told to a set of pictures” (Vane, 1981, p 319), but could also be beneficial in offering clues about the way social situations are interpreted by participants.

Instead of using the original picture set, which contains very old, black and white pictures, a new picture set was created for this experiment, see Figure 5 for an impression. This allowed for the creation of more up-to-date situations and better quality, colored images. The light settings in the pictures were made to resemble a neutral color temperature by using a grey card and adjusting the images afterwards using the program Adobe Lightroom. All actors in these pictures were friends of the author and in the age of 18-26. Out of a set of thirteen pictures, eight final ones were chosen based on a small pilot. These eight were rated most ambiguous with regard to people’s interpretation of the valence and the sociality of the situation, as well as people’s understanding of what was happening in the situation. Half of these pictures were based on situations portrayed in the original data set (pictures 1, 2, 5 and 6). The other half was based on scenarios created by the author (pictures 3, 4, 7 and 8). The pictures were presented based on a rotating scheme, so that the pictures were presented in a different order to each participant. The participants were instructed to ring a small bell on the desk in order to indicate when they were done with their description, because of which the time participants were presented with the light conditions varied. However, on average, each picture and the corresponding light condition was presented to participants for approximately two minutes.

Table 1 Average measured values of color temperature of light and illuminance in each lighting condition separately

Light placement Color temperature of light (K) Illuminance (lux)

Warm white lightSituation 2900 218

Participant 2917 196

Cold white lightSituation 5731 191


Neutral white lightSituation 4018 191


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Figure 5 Examples of pictures of our picture set; the upper pictures are based on the original pictures of the Thematic Apperception Test, the two lower pictures are based on own scenarios. See appendix C for the entire set.

3.4.1.1 Measuring social appraisalSocial appraisal as interpreted from participants’ descriptions of the situations was measured via to separate indicators: social valence; the number of positive and socially positive references in the description, and social distance; the distance between the evaluator and the persons present in the situation. Research indicates that social distance can be measured by exploring concrete and abstract language use. First, people in cultures viewed as interdependent (e.g. interacting in close proximity with others) are seen to use more concrete language than people from independent cultures in their description of events and emotions (Semin, Görts, Nandram and Semin-Goossens, 2002). Second, as grounded in construal level theory (Trope and Liberman, 2003), temporal distance seems to lead to a more abstract description of events. This same relationship has been found for both spatial and social distance (Bar-Anan, Liberman & Trope, 2006) and is also visible in language use; social distance is seen to relate to a more global way of processing information, leading to a tendency to describe (social) distance abstractly and (social) proximity concretely (Semin, 2007).

Social distance was investigated by evaluating the abstractness of the language used by participants to describe each situation. Each description was coded for abstraction level by the author and a second, independent, coder, according to the linguistic category model (LCM; Coenen, Hedebouw and Semin, 2006). This model was shown to effectively measure (social) distance as compared to participant’s own perceived inclusion of a person in the self (IJzerman and Semin, 2009). The LCM model differentiates between four ways of describing events in language, ranging from very concrete to very abstract; descriptive action verbs (e.g. Bryan kisses Amy), interpretive action verbs (e.g. Bryan caresses Maria), state action verbs (e.g. Bryan surprises Maria), state verbs (e.g. Bryan loves Maria) and adjectives (e.g. Maria is loveable; see Table 2).

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Table 2 Definitions and examples of the four categories of interpersonal predicates as defined in the Linguistic Category Model

Categories Definition Examples Scoring

Descriptive Action Verb (DAV)

Verb that refers to a single specific action with a

clear beginning and end, and with a physically

invariant feature.

Hit, yell, walk, …

1

(very concrete)

Interpretive Action Verb (IAV)

Verb that refers to a multitude of different

actions with a clear beginning and end that have

the same meaning but don’t share a physically

invariant feature.

Help, tease, avoid, … 2

State Action Verb (SAV)

Verb that refers to a behavioral event but

expresses the emotional consequence of an

action rather than referring to an action as such.

Surprise, amaze, anger,

…2

State Verb (SV) Verb that refers to an enduring cognitive or

emotional state with no clear definition of

beginning an end.

Admire, hate,

appreciate, …3

Adjectives (ADJ)Adjective that refers to a characteristics or

feature qualifying a person.

Honest, reliable,

aggressive, …

4

(very abstract)

Note. This table was adapted from Coenen, Hedebouw and Semin (2006, p.7).

For each separate description, instances of each category were counted and scored based on Table 2. The total number per description was divided by the number of instances scored to calculate the mean abstraction score. Although the first coder was not blind to the experimental conditions, a second coder was. An intercoder reliability of Kappa = 0.70 (p < 0.001) was found (9 out of 64 participants were coded by a second coder), which is found to be acceptable for exploratory research (Lombard, Snyder-Duch & Bracken, 2002). The following shows an example of this coding method, including a Dutch description of the upper left picture in Figure 4.

“Het rechter meisje verteld (IAV) iets naars (ADJ) aan haar beste (ADJ) vriendin en voelt zich hierbij kwetsbaar (SV) en ongemakkelijk (SV) vandaar dat ze wegkijkt (DAV). Haar vriendin (links) probeert haar te troosten (IAV) en gerust te stellen (IAV). Zij voelt zich geraakt (SV) en begrijpt (SV) de situatie.”

1(DAV) + 3(IAV) + 4(SV) + 2(ADJ) = 1(1) + 3(2) + 4(3) + 2(4) = 2727/10 = 2.7

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Table 3 Definitions and examples of the social valence coding scheme

Valence Definition Examples Scoring

Positive

Very positive, mention of multiple positive

actions/emotions

e.g. “The person is happy and feeling good.”

but also “The person is happy and talking

with his friend.”

+ 3

Positive, mention of one positive action/emotione.g. “The person is happy.” but also “The

atmosphere is cozy.”+2

Somewhat positive, no clear mention of positive

action/emotion, but reference to something

positive.

e.g. “The person is a friend.” Or “The two

persons get along.”+1

NeutralNo mention or global reference of positive or

negative action, or sentence contains equal

number of both

e.g. “The person is walking down the street.”

but also “One person is happy, the other

person is sad.”

0

Negative

Somewhat negative, no clear mention of

negative action/emotion, but reference to

something negative.

e.g. “The friendship has ended.” -1

Negative, mention of one negative action/

emotion

e.g. “The person is sad.” but also “The

atmosphere is not cozy.”-2

Very negative, mention of multiple negative

actions/emotions

e.g. “The person is sad and feeling bad.”

but also “The person is sad because her

relationship has ended.”

-3

Each sentence of a participant’s description was therefore coded for its social valence ranging from -3 (very socially negative) and +3 (very socially positive). The total number per description was calculated by adding up the values for each individual sentence (usually three, as this was requested from participants). An intercoder reliability of Kappa = 0.70 (p < 0.001) was found (9 out of 64 participants were coded by a second coder), which is found to be acceptable for exploratory research (Lombard, Snyder-Duch & Bracken, 2002). The following shows an example of this coding method, including a Dutch description of the upper left picture in Figure 4.

“Het linker meisje is de rechter aan het troosten. (+2) De rechter is bedroefd, hopeloos en verbitterd. (-3). De linker is bezorgd. (+2).2 + -3 + 2 = +1

3.4.2 AtmosphereBecause perceptions of a social situation could be guided by the atmospheric perception of the (social) environment, participants’ evaluation of the atmosphere inside the experimental room was measured using seventeen items of the atmospheric questionnaire originally developed by Vogels (2008). Sixteen variables were chosen

To investigate social valence induced by the situations, a second coding scheme was applied (see Table 3 for an overview). Social valence includes not only positive and negative descriptions (e.g. the person is happy), but also and more importantly, descriptions of social positive and negative events (e.g. the atmosphere is cozy).

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based on a selection made by Custers, de Kort, IJsselsteijn and de Kruiff (2010) in their research and the item “warm” was added because of our interest in color temperature of light effects. People were asked to rate the applicability of each variable on a five-point scale ranging from “not applicable at all” to “very applicable”. Four categories can be derived from the used variables: coziness (included “cozy”, “intimate”, “pleasant”, “safe” and “warm”), liveliness (included “lively”, “stimulating”, “inspiring” and “cheerful”), tenseness (included “tense”, “terrifying”, “oppressive” and “threatening”) and detachment (included “business”, “formal”, “cool” and “chilly”). The variables were presented to participants in Dutch (see Vogels, 2008 for translations). These dimensions showed internal consistency values of α = 0.91, α = 0.82, α = 0.91 and α = 0.91 respectively. Next to this, participants were also asked to rate the amount in which they found the light settings to be a positive distracter in general (“The lighting offers me a positive distraction”) on a five-point scale ranging from “not applicable at all” to “very applicable”. Lastly, participants were asked to indicate their perceived temperature inside the room where the light manipulation was visible on a five-point scale ranging from “cold” to “warm”.

3.4.3 Need to belongGardner, Pickett and Brewer (2000) showed that people who had a high need for sociality (e.g. were hungry for sociality) were more sensitive to social cues around them. Since one of the variables we are measuring is the level of sociality participants attribute to certain situations, it is important to get information about participant’s personal feelings towards sociality. For this reason, two questionnaires probing ‘need to belong’ and ‘need for affiliation’ were administered. Need to belong concerns people’s need to maintain a minimum of personal relationships (Baumeister and Leary, 1995). This concept was measured via the ‘Need to Belong Scale’ developed by Leary, Kelly, Cottrell and Schreinedorfer (2001), translated into Dutch. The five-point scale includes items such as “If other people don’t seem to accept me, I don’t let it bother me (reverse-coded)” and “I have a strong need to belong”. Internal consistency for this scale was α = 0.78. Need for affiliation was measured via the Dutch version of the ‘Need for Affiliation Scale’ developed by van Tilburg (1988). This five-point scale included items such as “I want to talk to others about how I feel, about my inner experiences” and “I try to cope with sorrows on my own (reverse-coded)”. Internal consistency for this scale was α = 0.86. Participants answered both questionnaires on a seven-point scale ranging from “not at all characteristic of me” to “extremely characteristic of me”.

3.4.4 MoodThe initial mood state participants were in could potentially affect their evaluation of the social situations and the effect of atmospheric variables (Vogels, 2008). For this reason, participants’ mood was measured via a short version of the mood questionnaire used by Beute and de Kort (2013) presented in Dutch. Participants answered “How do you feel right now?” for thirteen items. Answers were indicated on a five-point scale ranging from “not at all” to “very much”. Three dimensions were retracted from these questions to measure mood: energy (included “energetic”, “sleepy”, “alert”, “tired” and “attentively”), tenseness (included “relaxed”, “tense”, “nervous”, “at ease” and “calm”) and positive affect (included “satisfied”, “happy” and “sad”). These dimensions showed internal consistency values of α = 0.81, α = 0.75 and α = 0.74 respectively.

3.5 Procedure

Upon arrival, participants were guided to the participant area of the Lightinglab and asked to read and sign the consent form (see Appendix E). Next, they were explained about the procedure and tasks they would be performing (I). The experiment leader then left and the experiment started. Participants were first asked to fill in a short mood questionnaire (M). After this, participants performed the main task, the situation appraisal task. The pictures of social situations (P) were presented to participants and light conditions were changed alternately

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(resembled by the blue and red squares in Figure 6). Next, participants filled in the atmospheric questionnaire (A) in each light condition and filled in the need to belong and need for affiliation questionnaires (S). The experiment ended with some demographic questions, questions about the light and a questionnaire about whether the participant knew one or more of the persons in the picture (Q). Overall, the experiment took about 30 minutes. Figure 6 shows an overview of the experiment in one of the light placement conditions.

Figure 6 Overview of the experiment; colored squares resemble the color temperature of light condition (red representing warm white light, blue representing cold white light). I = introduction, M = mood questionnaire, P = photograph, A = atmospheric questionnaire, Q = closing questionnaire.

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Results study 14The aim of the first experiment described in this paper was to explore whether people’s appraisal of ambiguous social situations would be influenced by color temperature of light. Furthermore, we wanted to investigate whether this influence of color temperature of light depended on whether the color temperature was presented on the situation (situation light placement) or the color temperature was presented on the participant (participant light placement). To evaluate this, participants’ descriptions of the pictures were analyzed via two different coding measurements; social distance (using the Linguistic Category Model) and social valence. Participants’ evaluation of the atmosphere in the separate light conditions was also analyzed. This section describes the analyses of this data. All data of all dependent variables was normally distributed.

The means of all pictures in both light conditions were compared to discover whether there were large discrepancies between pictures, but only some slight differences were found and most pictures scored comparably. Moreover, analyses without the few pictures that showed higher or lower mean-scores did not significantly alter the results. All pictures were therefore used in the final analyses. For each color temperature of light, an average value was calculated per participant by averaging the standardized scores of the four pictures in each light condition. Standardized scores were used to control for the slight difference found between the effects of the pictures.

4.1 Main analysis

In order to assess the influence of color temperature of light, repeated measures ANOVAs were conducted comparing cold white light to warm white light on social distance and social valence separately. Before analysis, outliers were removed from the data that showed standardized scores of < -3 or > 3.

4.1.1 Social distanceA repeated-measures ANOVA was conducted including color temperature of light as the within-subject variable and the light placement condition as a between-subject factor. Although no main effect of light temperature was found (F(1,62 = 1.21, p = 0.276), the analysis did indicate an interaction effect of color temperature of light * light placement (F(1,62) = 5.77, p = 0.019). Analyses indicated that the difference between the cold and warm white light conditions is larger for the situation light placement compared to the participant light placement (see Figure 7).

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Figure 7 Mean values of social distance per color temperature of light in both light placement conditions. Bars represent 95% confidence intervals.

To analyze this effect further, repeated measures ANOVAs were also conducted on participants in the situation light placement and the participant light placement separately, again including color temperature of light as a within-subject variable. These analyses indicated that the effect of color temperature of light was significant in the situation light placement (F(1.31) = 8.20, p = 0.007), but not significant in the participant light placement (F(1,31) = 0.68, p = 0.417). In the situation light placement, the effect was in the expected direction; participants in the warm white light condition showed a lower average LCM value (thus, more concrete language use) compared to the participants in the cold white light condition. Since concrete language use is associated with a smaller social distance to others and thus a higher social appraisal (Semin, 2007), these results support our hypothesis 1. Moreover, the effect was only visible in the situation light placement, supporting hypothesis 2. See Table 4 for an overview of the mean differences for each light placement condition.

Table 4 Mean values of social distance measurement per light condition and light placement

Color temperature of light

Warm Cold

Light placementSituation * M = -0.24, SE = 0.09 M = 0.03, SE = 0.11

Participant M = 0.13, SE = 0.11 M = 0.03, SE = 0.09

* p < 0.05

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4.1.2 Social valenceA repeated-measures ANOVA was conducted including color temperature of light as the within-subject variable and the light placement condition as a between-subject factor. The covariate tenseness (mood variable) was significant (F(1,61) = 5.3, p = 0.025), indicating participants in the experiment indicated to feel differently with regards to tenseness. With this variable included, no main effect of color temperature of light (F(1,61 = 0.45, p = 0.506) or interaction effect of color temperature of light * light placement (F(1,61) = 1.71, p = 0.196) was found. See Table 5 for an overview of the mean values for each measurement. Color temperature of light thus was not found to affect social appraisal as measured via this variable.

4.2 Atmospheric variables

To explore whether participants’ impression of the two light settings differs, and whether the light placement affected these impressions, the effect of color temperature of light on atmosphere perception was also investigated. Although no hypotheses were set-up for this investigation on beforehand, because of the exploratory nature of this study we hoped to gain more insight into the possible underlying effects of color temperature of light on social appraisal in this way. Therefore, a repeated measures ANOVA was conducted on the four atmospheric variables (coziness, liveliness, tenseness and detachment) separately. Before analysis, outliers were removed from the data that showed standardized scores of < -3 or > 3.

Covariates gender (F(1,57) = 4.6, p = 0.036; females rated the light as tenser in general (M = 2.18, SE = 0.09) than males (M = 1.91, SE = 0.08) and energy (mood variable; (F(1,57) = 5.5, p = 0.023) showed a significant effect in the analysis for the atmospheric variable tenseness and were included in this analysis. Overall, the analyses indicated that all effects were in the expected directions; participants rated the warm white light as significantly more cozy, more lively, less tense and less detached than the cold white light (see Table 6 for an overview of the mean values for each atmospheric variable).

Table 5 Mean values of social valence measurement per light condition and light placement


Warm Cold

Light placementSituation M = 0.069, SE = 0.079 M = -0.079, SE = 0.081

Participant M = -0.003, SE = 0.101 M = 0.04, SE = 0.11

* p < 0.05

Table 6 Mean values of participant’s interpretations of the atmospheric variables in both color temperature of light conditions. Bars represent 95% confidence intervals.


Warm Cold F-value p-value

Coziness M = 3.49, SE = 0.08 M = 1.65, SE = 0.06 (1,61) = 281.4 < 0.001

Liveliness M = 3.03, SE = 0.08 M = 2.15, SE = 0.07 (1,61) = 63.5 < 0.001

Tenseness M = 1.57, SE = 0.06 M = 2.54, SE = 0.10 (1,57) = 89.2 < 0.001

Detachment M = 1.63, SE = 0.06 M = 3.77, SE = 0.09 (1,61) = 63.5 < 0.001

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Light placement did not show a significant effect in any of the analyses. However, a significant interaction effect for color temperature of light * light placement was found in the tenseness variable (F(1,57) = 10.2, p = 0.002). Participants rated the cold white light as more tense when the light was placed on the situation (M = 2.80, SE = 0.14) than when the light was placed on the participant (M = 2.24, SE = 0.13). The same trend was visible for the warm white light; when light was placed on the situation the light was rated less tense (M = 1.52, SE = 0.09) than when placed on the participant (SE = 1.61, SE = 0.08).

4.3 Mediation analyses

Based on these findings, participant’s evaluation of the atmosphere might (partly) explain, or mediate, the effect of the color temperature of light on the evaluation of the situation as discovered in the main analysis. To explore this, a correlation analysis was conducted including social distance as measured via the LCM coding measurement and all four atmospheric variables; see Table 7. This data already indicates that none of the atmospheric variables correlate significantly with the social distance measurement. However, because color temperature of light did seem to have a large effect on the

Figure 8 Overview of the ratings of the atmospheric variables in both color temperatures of light

Warm white light thus showed higher values for the ‘social’ atmospheric variables (coziness and liveliness) compared to the cold white light. Cold white light on the other hand showed higher ratings of detachment compared to the warm white light condition; see Figure 8.

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atmospheric variables, we decided to still conduct a mediation analysis exploring the two atmospheric variables that showed the highest correlations (coziness and detachment), since these variables are also related most with sociality.

Because both variables correlate highly, two separate mediation analyses were conducted. In order to obtain the necessary regression coefficients to perform the mediation analyses, two separate linear mixed model analyses (LMM) were performed following the mediation analysis as described by Baron and Kenny (1986) and by using Sobel tests (Zhao, Lynch & Chen, 2010). Social distance as measured via the LCM coding scheme was included as dependent variable. Coziness and detachment were included as dependent variables in each of the analyses, respectively. Participant number was included as an independent random intercept, to retain the within-subject structure of the experiment. The results of these mediation analyses of coziness and detachment on social distance are summarized in Table 8. Although the analysis showed a significant effect of color temperature of light on the two atmospheric variables, there is no significant effect of the atmospheric variables on social distance directly (stage 2 effect). Participants’ perceived atmosphere as measured by coziness and detachment thus could not explain the effect of color temperature of light on social distance.

Table 7 Correlation matrix of social distance and four atmospheric variables

Social distance

Coziness Liveliness Tenseness Detachment

Social distance

Pearson correlation 1 -0.167 -0.129 0.046 0.170

Significance 0.188 0.308 0.719 0.179

CozinessPearson correlation 1 0.827 0.009 -0.866

Significance <0.001 0.946 <0.001

LivelinessPearson correlation 1 -0.099 -0.654

Significance 0.435 <0.001

TensenessPearson correlation 1 0.069

Significance 0.588

DetachmentPearson correlation 1

Significance

Table 8 Mediation of the effect of color temperature of light on social distance by coziness and detachment (table shows results of two separate mediation analyses)

Independent variable

Total effect (c)

Direct effect (c’)

MediatorStage 1

Indirect effect (a)

Stage 2 Indirect effect (b)

Indirect effect (ab) a

Light temperature

(cold vs. warm white light)

-0.27 **

-0.24 Coziness 1.88 *** 0.02 -0.19

-0.32 Detachment -2.25 *** 0.02 0.23

* p < 0.10. ** p < 0.05. *** p < 0.001.a this column shows Sobel-test statistics and one-sided significance tests.

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Because the first mediation analysis indicated that atmospheric perception could not explain the results found in our main analysis, we also explored some other variables that could explain a direct effect of color temperature of light on social appraisal, namely ‘perceived temperature’ (indication of participants’ perception of the temperature in the room with the induced light condition) and ‘positive distracter’ (indication of the extent to which participants found the light to be a positive distracter). Again, a correlation analysis was conducted first to explore these variables; see Table 9.

Table 9 Correlation matrix of social distance, perceived temperature and positive distracter

Social distance Perceived temperature Positive distracter

Social distance

Pearson correlation 1 -0.198 -0.037

Significance 0.123 0.770

Perceived temperature

Pearson correlation 1 0.696

Significance <0.001

Positive distracter

Pearson correlation 1

Significance

Although this analysis already indicated that both variables did not correlate with the social distance measurement, two mediation analyses were conducted to explore this relationship in more detail. Perceived temperature and positive distracter were included as dependent variables in each of the analyses, respectively. Participant number was included as an independent random intercept, to retain the within-subject structure of the experiment. Color temperature of light again significantly influenced both perceived temperature (lower temperatures were perceived when cold white light was visible) and positive distracter (warm white light was indicated as a more positive distracter than cold white light), but no significant effect of either variable was found on social appraisal directly. See Table 10 for an overview of the results.

Table 10 Mediation of the effect of color temperature of light on social distance by perceived temperature and positive distracter (table shows results of two separate mediation analyses)

Independent variable

Total effect (c)

Direct effect (c’)

MediatorStage 1

Indirect effect (a)

Stage 2 Indirect effect (b)

Indirect effect (ab) a

Light temperature

(cold vs. warm white light)

-0.27 **

-0.35 **Positive

Distracter1.44 *** -0.05 0.65

-0.18Perceived

Temperature2.55 *** 0.03 -0.32

* p < 0.10. ** p < 0.05. *** p < 0.001.a this column shows Sobel-test statistics and one-sided significance tests.

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In this experiment we explored whether the color temperature of light (cold vs. warm) as well as the placement of this light (either the situation was viewed in the different light settings or participants themselves were placed in different light settings) would influence participants’ appraisal of ambiguous social situations displayed on static 2D images. Some prior studies (Baron et al., 1992; van ‘t Sant, 2012) have shown that warm white light induces more pro-social behavior and leads to more positive evaluations of fictive persons. By evaluating participants descriptions of these situations we explored whether warm white light would lead people to appraise the situation more socially via two different measurements; social valence and social distance and whether these results were guided by light acting as a situational cue for the environment.

5.1 The social effect of color temperature of light

Results of the analysis of social distance showed that participants did evaluate the situations in a more social way in warm white light (2900 K); descriptions showed a higher level of concrete language use, which is associated with lower social distance, or higher social proximity towards the people in the situation (IJzerman and Semin, 2009). The social valence measurement did not show the same significant difference. These results therefore partially support our hypothesis 1, and offer some indication that warm white light leads to a more social appraisal of a situation and makes people feel closer to the people therein.

However, these results were guided by the placement of the light settings; a significant effect for color temperature of light was only visible when the light settings were induced in the situation. When the light was changed in the part of the room the participant was in, there was no difference between participants’ appraisals of the situation in the warm or cold white light. This supports our hypothesis 2, indicating that the effect of color temperature of light is more evident when the light manipulation is visible in the situation itself and thus directly linked to the situation.

It also offers evidence for our second pathway, in that the effect of the color temperature of light is mainly due to its potential for acting as a positive situational cue. One potential mechanism behind the effect of color temperature of light acting as a situational cue could be the effect it has on atmospheric evaluations of the environment. Although no hypothesis was set up for this mechanism, because of the exploratory nature of this experiment we decided to still analyze this effect. Indeed, results of participants’ evaluation of the atmosphere in the warm white light compared to the cold white light showed that they differed significantly on all four atmospheric variables. Warm white light was rated as more cozy, more lively, less tense and less detached than cold white light. Since coziness is often related to a social situation, it might be stated

Discussion study 15

Warm white light can lead to a more social appraisal of a situation, specifically making people feel closer to the people in the situation.

Social appraisal is only affected when the color temperature of light is directly visible in the situation itself.

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that warm white light is generally rated as more social. However, a mediation analysis showed that there was no significant effect of the atmospheric evaluation on social distance directly, indicating the effect of color temperature of light on atmosphere cannot explain the effect of color temperature of light on the evaluation of social distance for the social situations. Moreover, although other research has indicated a significant effect of temperature on sociality (IJzerman and Semin, 2009) and warm white light was indeed rated as warmer in our experiment, this variable did not mediate the overall main effect. The extent to which participants rated the light as a positive distracter also could not explain the main effect found in this experiment. Although some possible mechanisms have thus been reviewed, none of these variables were seen to explain the positive effect of color temperature of light on social appraisal. More research will be needed to further investigate the possible underlying effects.

As other studies have shown, the positive effects of color temperature of light might be (partly) attributed to participants’ mood or affective state (Baron et al., 1992) or personal preference (Knez, 1995). However, in this study, we found no indications that changes in participants’ mood at the start of the experiment influenced their appraisal of the situations. Also, gender effects for which Knez (1995) found a difference in preference, were only found in one atmospheric variable; tenseness (females showed higher overall ratings in tenseness of the light settings). The main effects of color temperature of light on social appraisal were not affected by gender. Moreover, since the effects of color temperature of light were not present when the light manipulation was placed on the participant, the effect is presumably more guided by light acting as a situational cue and less by people’s mood stated or personal preferences for the different light settings. However, more research is needed to analyze this effect more effectively.

The results of this first experiment together show that 1) warm white light compared to cold white light can induce a more social appraisal of ambiguous situations and 2) that this effect is largest when the situation itself is viewed in the light setting. Overall, this shows that when situations are ambiguous, people are seen to use other cues in the situation to make their judgment about the situation, in this case the different light settings. Color temperature of light can thus serve as a situational cue in ambiguous situations and can guide people’s appraisal in this way. Moreover, this study shows that warm white light can reduce social distance between people. Since an increase in social distance is seen as one of the causes for creating a feeling of anonymity (Hirsch et al., 2011) and in turn aggression (e.g. Diemer, 1979; Page and Moss, 1976) warm white light could in turn benefit the process of reducing aggressive behavior. To further investigate the underlying mechanisms however, more research will be needed.

5.2 Methodological paradigm

5.2.1 Limitations Analyses of the individual photographs indicated that although there were some (slight) differences in participants’ evaluations of the photographs, these did not significantly influence the overall results. Moreover, we decided to make use of standardized values to further minimize any differences between photographs. However, because we chose to create photographs in ‘natural’ situations (e.g. some were made outside) to best reflect real life conditions, the photographs contain different types of colors and environmental elements. For example, some photographs contain various nature elements (trees, bushes), which could also affect the positivity induced by the photograph (Heijboer, 2012) and might have reduced the effect of color temperature of light. However because of the small differences between photographs, we feel this effect has had little consequence for our research purposes.

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Due to our experimental set-up, there was always a difference between the color temperature of light in one part of the room compared to the other part (e.g. neutral compared to either warm or cold white light). We chose this paradigm because we wanted to avoid too much complexity in the comparison of the light manipulations. It might be that the results that we found were not affected by the absolute effect of color temperature of light, but by the difference in light settings between the observer and the situation. This was especially noticeable when the light setting was induced in the part of the room the participant was in; when this part of the room was lit by warm white light, the light placed on the situation seemed somewhat cold due to the difference between both light settings. However, no significant results were found for the light settings in the in this part of the room, indicating this effect was less strong than when light was placed directly on the situation.

One other effect of this set-up might be that participants could have adapted to the light settings more easily when the light was placed in their own surroundings. Their attention was not directed to their own surroundings, but towards the situation in the other part of the room instead, making the light manipulation in this part of the room (warm or cold white light) less noticeable. We tried to minimize this effect by employing a within-subject light setting that changed approximately every 2 minutes, but it is still possible that this adaptation could have influenced the results.

5.2.2 Novel aspects of methodologyDespite these limitations, this research contributes to the research about the effects of light on social behavior. By creating a new research paradigm, we were able to independently assess several effects of light on social evaluations (e.g. the effect of color temperature of light itself and of the placement of a light setting). To our knowledge, no research investigating the effect of the placement of the light on social appraisal has been done before. Moreover, little research has been done investigating the effects of (color temperature of) light on the appraisal of social situations. The results of this study offer more insights into the effect that color temperature of light could have on sociality, and might explain why others (e.g. Baron et al., 1992) have found people to evaluate people more positively in warm white light. Moreover, this research could serve as a starting point for the requirements of the design of interactive lighting to potentially reduce aggressive behavior.

5.3 Real-life effects of warm white light

Although we already found some interesting results in our first experiment indicating that warm white light can positively influence people’s social appraisal of an ambiguous situation. However, because we are interested in whether warm white light could potentially guide people’s actual behavior, we decided to set-up a second experiment in order to explore the influence of color temperature of light on social behavior more extensively. Building upon the results we found in our first experiment, this second experiment will investigate whether warm white light can also be beneficial in guiding more positive social behavior.

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Study 2 Effects of light on social behavior6In light of our exploration of the beneficial effects of color temperature of light in potentially de-escalating behavior, it is of importance to also gain insight into the effects of color temperature of light on real-life social behavior outside of the laboratory. Although some laboratory studies have indicated effects of color temperature of light on various aspects of behavior (e.g. more collaboration, more donation of money; Baron et al., 1992), to our knowledge, no studies exist investigating the influence of color temperature of light on social behavior in various light settings outside of the laboratory. However, next to the implemented light settings, a variety of other situational cues also exist in real-world environments that could potentially influence social behavior. It is thus important to also examine whether the positive effects of warm white light we discovered in our first experiment (e.g. leading to a more social appraisal of the situation) will hold in real-word environments and whether these effects can be extended to real-life social behavior. In this second experiment we therefore wanted to explore the influence of warm white light on social behavior in real-life social events, in order to investigate whether warm light could eventually be employed to reduce aggressive behavior.

An interesting way to investigate this is by exploring and evaluating people’s interactions in public settings. Interactions are often seen as conversations, however several types of interactions can also occur without speaking, including for example glances at others or only sharing a common presence (Patterson, Webb and Schwartz, 2002). People often adjust or react to the presence of others, for example by glancing at others to indicate intrest (Patterson et al., 2002) or adjustng posture when others are near by. Milgram, Liberty, Toledo and Wackenhut (1986) investigated these types of social interactions between people in an interesting way. In their experiments, they observed people’s reactions to intrusions of confederates who jumped the queue in waiting lines. According to the authors, a waiting line is considered a small-scale social system that is regulated by rules and standards deemed appropriate for the situation (e.g. join at the back of the queue). In most cases, people were seen to react to violations of these social rules by objecting verbally in order to expel the intruder from the waiting line. Patterson et al. (2002) have also investigated these types of behavior in a slightly

Figure 9 People waiting in a waiting line, showing social presence in a small-scale social system (retrieved from http://planetterry.wordpress.com/tag/waiting-in-line/)

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different way and explored how one person’s interactions could affect another person’s interactions in passing encounters between pedestrians. They found that approaching pedestrians were more likely to glance at a confederate when this person looked and smiled at the pedestrian instead of merely looked or avoided looking at the pedestrian.

Overall, these studies show that observing people’s interactions with each other might offer some insights into the social order and beliefs the people interacting (Patterson, 2008) and perhaps their social behavior with surrounding people in public settings. By employing different types of lighting conditions (warm or cold white light) in similar types of social situations, we want to investigate whether warm white light could lead to a more positive, or less negative, reaction to the others in the environment. In the current study, we focused our observations on a commonly used public space at the university; the cafeteria. By observing people’s interaction at the register, specifically people’s interactions directed towards the cashier, we want to investigate whether this type of social behavior can be influenced by color temperature of light.

Based on research concerning color temperature of light (Baron et al., 1992) and the results of our own study, we hypothesized that people reaching the register when the warm white light setting was in place would 3) show more positive interactions (e.g. look happier, make more eye-contact with the cashier) and 4) be more likely to communicate with the cashier (e.g. courtesies, conversation) compared to when a cold white light setting was in place.

6.1 Design

In this second part of the study, we wanted to explore people’s real-life social behavior in different light conditions. During two weeks of observations, we explored whether social interactions would be affected by color temperature of light (warm, 2700 K vs. cold, 5600 K). To investigate this, we observed people’s spontaneous behavior while purchasing food in a cafeteria, and especially the social interactions between customers and the cashier at the cafeteria. This setting was chosen because the interactions between the customers and the cashier are similar for each customer and each interaction contains the same three phases that have a clear beginning and end (arrival, paying and leaving). Moreover, the interactions are almost always very short, making it possible to observe many customers every day.

6.2 Observed participants

On average, about 20-30 customers were observed at the register setting each day, which was about one third of the people passing the register each day. During crowded periods when a line was formed at the register, every third person was observed. This was manageable in the time needed for recording the data and still allowed for the observation of as many customers as possible. During less crowded periods however, when the time between customers arriving at the register was longer, almost every customer was observed. In total, this resulted in 222 observed events (see Table 6), 179 of which were males and 43 of which were females due to the large population of males attending and working at the university. Due to the observed age of the customers, we assume that most people were students (120; estimated age of 18-30) or staff-members (83; estimated age of 30-50) working at the university. The remainder (16) were estimated to be older than 50 and it was therefore unclear whether they were staff-members or people visiting the university for other reasons.

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6.3 Setting

The observations were conducted at one of the registers in the main cafeteria of the University of Technology, Eindhoven and lasted for two full weeks, during exam time Besides this register, there were two other registers close by. A luminaire was present next to each of the registers (see Figure 10 for an impression of the cafeteria).

Figure 10 Impression of the cafeteria, the observed register (middle) and the other registers (right)

The lighting in the luminaire next to the observed register was adjusted to create the wanted lighting conditions. The lighting at the other registers was not adjusted. Because of the placement of the lamp, both the person being observed (observant) and the entire interaction with the cashier were covered by the light setting.During the observations, the cashiers alternated each other frequently. In total, there were approximately seven different cashiers during the time of observations. All of them were females, ranging in age from about 30 to 50. The cashiers were told that the study included different light settings and the observation of people’s behavior in these light settings, but were not explained about the hypothesized direction of these effects as to not affect their interaction with the customers.

6.3.1 Light manipulationsThe original lighting near the register (Osram Dulux 18W/830, 3000 K) was changed by replacing the light bulbs (PL-lamps) in a luminaire near the register with either luminaires of a higher color temperature (Osram Dulux D/E 18W/865, 6500 K) or of a lower color temperature (Osram Dulux D/E 18W/827, 2700 K). Light measurements were conducted at all registers; see Table 11. A complete overview of the light measurements can be found in Appendix G.

Table 11 Overview of the average light measurements of color temperature of light and illuminance at all registers (register 3 is the observed register with the induced light settings)

RegisterColor temperature of light

(K)Illuminance (lux)

Luminance (cd/m^2)

Warm white light 3 2725 205 3.86 * 10^3

Cold white light 3 5584 221 3.72 * 10^3

Neutral white light1 2996 89

2 2746 58

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Taken together, the light manipulations resulted in a cold white light condition (5600 K) and a warm white light condition (2700 K) respectively, as measured on the eye of a person standing in front of the register. The light bulbs in the luminaire near the other two registers were not changed, inducing approximate light conditions of 3000 K, 90 lux (register 1) and 2800 K, 60 lux (register 2), measured on the eye of a person standing in front of the register. See Figure11 for an impression of the two light conditions at register 3.

The light condition at the registered was changed from warm white light to cold white light or opposite every day. Moreover, the two weeks of observations were counterbalanced to observe each corresponding day in two different light conditions. Figure 12 shows the distribution of the light conditions across the two weeks.

MONDAY

Week 1

TUESDAY WEDNESDAY THURSDAY FRIDAY

Week 2 Week 2 Week 2 Week 2 Week 2Week 1 Week 1 Week 1 Week 1

Figure 12 Overview of color temperature of light conditions for each day in both observation weeks

Figure 11 Light conditions at the register; warm (left) and cold (right) white light

6.4 Observational measurements

Observations took place during lunchtime (between 11.30-13.30), since most people were present in the cafeteria during these hours to buy lunch or drinks. To mask the observation study as much as possible, the observer was seated slightly hidden behind a mat plate behind the register. From this vantage point, the observer could view people’s faces and actions and reactions towards the cashier. The first day of observations (a Monday) was used as a pilot for the observation scheme and this data was discarded.

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6.4.1 Observation schemeIn order to objectively assess the amount of social behavior people showed towards the cashier, four categories of codes were determined based on three elements of the social interactions taking place at the register. These categories included facial expressions (e.g. smiling), viewing behavior (e.g. eye contact with the cashier), overall impression (positive/negative) and communication (e.g. saying hello and goodbye, asking to pay with card), see Table 12. Every customer’s behavior was coded on all these elements. Behavior of each customer was observed from the moment a customer walked up to the register until a customer left. Behavior was recorded for three different interaction phases; arriving at the register, paying for something and leaving the register, with the exception of communication since this was bound to certain phases (e.g. greeting only took place upon arrival). It was chosen to distinguish between these phases, which resemble specific and well-defined parts of the entire interaction, because it was thought that behavior might be different for the specific categories (e.g. communication types such as greeting would be different). The entire coding scheme as used during the observations can be found in Appendix H. In order to better interpret the results, the category viewing behavior was later recoded so that each measurement stated whether the customer had either looked at the cashier or not at all. Also, because of the small number of costumers who paid via debit card (44 %), this category was recoded into either indicating to pay via debit card (verbally and non-verbally) or not at all.

6.5 Procedure

Observations took place each day between 11.30 and 14.00. Everyday day, the color temperature of light was changed. Each observation started when a customer walked up to the register and ended when the customer left the register, leading to observations of approximately a few minutes each. Firstly, the gender and estimated age of the observant was noted. The observer then observed and recorded the social interactions undertaken by the customer based on the coding scheme. No interaction was made between the observer and the customer during this time. When the customer was seen to notice and look at the observer before the observation was finished, this customer was deleted from the observation data. This happened in approximately 10% of all observations.

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Table 12 Overview of coding scheme for the observation of behavior at the register.

Coding categoryMeasurement

phaseDescription

Behavioral responses

Recoding of responses

Facial expression

Arrival

Paying

Leaving

What does people’s facial

expression best represent?

Smile

Neutral

Frown

Viewing behavior

Arrival

Paying

Leaving

Where do people focus their

visual attention on most of the

time?

Cashier

Surroundings

Payment action

Made eye-contact

with the cashier

Never made eye-

contact with the

cashier

Overall impression

Arrival

Paying

Leaving

Is the impression of the person

(including interaction style)

positive or negative overall?

Very positive

Somewhat positive

Neutral

Somewhat negative

Very negative

Communication

Arrival

Leaving

How do people make courtesies

with the cashier when they arrive

(greeting) or leave (thanking and

saying goodbye?)

Verbally

Non-verbally

Not at all

Arrival

Paying

Leaving

Do people have a verbal

conversation with the cashier

during the interaction?

Yes

No

PayingDo people indicate when they

want to pay by debit card?

Verbally

Non-verbally

Not at all

Did not pay by card

Indicated to pay by

card

Did not indicate to

pay by card

Did not pay by card

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Results study 27In this observation study, we wanted to explore whether real-life social behavior would also be affected by color temperature of light. To investigate this, people’s interactions with a cashier at the register were observed and coded in two light conditions (warm, 2700 K vs. cold 5600K). To compare the findings of the categorical data of our observations between the two light conditions, chi-squared tests were conducted for three of the coded variables separately (facial expression, viewing behavior and communication; including conversation and courtesies). To analyze the category overall impression, individual independent t-tests were conducted with color temperature of light as a grouping variable, because this variable was coded on a scale from 1 – 5.

7.1 Facial expression

Analysis of the data of the facial expression variable indicated that customers in the warm white light condition smiled more often (45.5 %) and frowned less often (5.3 %) than customers in the cold white light condition (43.4 % and 11.5 % respectively, see Table 13 for detailed results). A chi-square test comparing facial expression data in both color temperature of light conditions indicated that there was a significant difference between facial expressions in both groups (χ2 (2, N = 659) = 8.58, p = 0.015). The number of cases here (N) resembles all recorded facial expressions across the three phases of the interaction; in general, this means that for each customer, three facial expressions are included (taking into account some missing data). To further explore this effect, the facial expression data was also analyzed per interaction phase. This was done because during the pilot, it was seen that behavior was quite different for each interaction phase, especially when comparing arrival and leaving to paying.

7.1.1 Arriving at the registerFacial expression data in this interaction phase indicated that customers smiled slightly more often in the warm white light (54.7 %) compared to the cold white light (53.2 %). Customers also frowned less often in the warm white light (4.7 %) compared to the cold white light (10.6 %). A chi-square test comparing both groups indicated a trend between the two light conditions (χ2 (2, N = 222) = 2.96, p = 0.07). Overall facial expression was thus significantly more positive in the warm white light. See Table 16 for more detailed results.

7.1.2 Paying for somethingDuring the actual payment, customers in the warm white light also smiled more in the

Table 13 Overview of the results of the chi-square test for customers’ facial expression in both light conditions including all interaction phases


Facial expression Warm (n = 380) Cold (n = 279)

Percentage Absolute Percentage Absolute

Smiling 45.5 % n = 173 43.4 % n = 121

Neutral 49.2 % n = 187 45.2 % n = 126

Frowning 5.3 % n = 32 11.5 % n = 20

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warm white light (28.6 %) compared to the customers in the cold white light (19.6 %). Moreover, fewer customers frowned when in the warm white light (9.5 %) compared to customers in the cold white light (16.3 %). See Table 16 for more detailed results. A chi-square test revealed that the difference between both light conditions was significant (χ2 (2, N = 218) = 3.76, p = 0.039). Again, overall facial expression was thus significantly more positive in the warm white light.

7.1.3 Leaving the registerWhile leaving, fewer customers frowned in the warm white light (1.6 %) compared to the customers in the cold white light (7.5 %). However, fewer people also smiled in the warm white light (53.2 %) compared to the cold white light (57 %). See Table 14 for more detailed results. A chi-square test again revealed a significant effect of color temperature of light (χ2 (2, N = 219) = 5.97, p = 0.013).

Table 14 Overview of the results of the chi-square tests for customers’ facial expression in both light conditions


Interaction partFacial

expressionWarm (n = 130) Cold (n = 92)


Arrival

Smiling 54.7 % n = 70 53.2 % n = 45

Neutral 40.6 % n = 52 36.2 % n = 34

Frowning 4.7 % n = 6 10.6 % n = 10

Payment

Smiling 28.6 % n = 36 19.6 % n = 18

Neutral 61.9 % n = 78 64.1 % n = 59

Frowning 9.5 % n = 12 16.3 % n = 15

Leaving

Smiling 53.2 % n = 69 57 % n = 53

Neutral 45.2 % n = 57 35.5 % n = 33

Frowning 1.6 % n = 2 7.5 % n = 7

In general, this data showed that people tended to smile more and frown less in the warm white light condition (with the exception of leaving the register), offering support for hypothesis 3. Figure 13 shows an overview of the facial expressions in both light conditions.

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Figure 13 Overview of facial expressions in both light conditions, per interaction part

7.2 Viewing behavior

Analysis of the data of viewing behavior, which was recoded into either making eye-contact with the cashier during one point of the interaction or never making eye-contact, indicated more customers in the cold white light made eye-contact (44 %) compared to customers in the warm white light (38.2 %), see Table 15. However, a chi-square analysis comparing viewing behavior in both light settings indicated that there was no significant difference between the two groups (χ2 (1, N = 645) = 2.18, p = 0.145).

7.2.1 Interaction phasesUpon arrival (χ2 (1, N = 217) = 2.15, p = 0.155) and during payment (χ2 (1, N = 213) = 0.796, p = 0.406), no significant difference was found between the number of times customers made eye-contact with the cashier.

When leaving the register, a trend appeared (χ2 (1, N = 215) = 3.27, p = 0.074). People in the cold white light made eye-contact with the cashier more often when they left the register (52.7 %, N = 48) compared to people in the warm white light (40.3%, N = 50). This contradicts our hypothesis 3 in that more positive interactions would occur (e.g. making more eye-contact) in the warm white light.

Table 15 Overview of the results of the chi-square test for customers’ viewing behavior in both light conditions


Viewing behavior Warm (n = 372) Cold (n = 273)


Made eye-contact 38.2 % n = 142 44.0 % n = 120

Made no eye-contact 61.8 % n = 230 56.0 % n = 153

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7.3 Overall impression

To analyze customers’ overall impression, an independent t-test was conducted including overall impression as a dependent variable and color temperature of light as a grouping variable. Results of this analyses indicated that there was a significant difference in customers’ overall impression in both light conditions (t(663) = -2.05, p = 0.040). Customers in the warm white light showed a more positive overall impression (M = 3.46, SE = 0.84) compared to customers in the cold white light (M = 3.31, SE = 0.98), see Figure 14. This partly supports our hypothesis 3, in that more positive interactions would occur in warm white light. However, both values are very close to the neutral point (3), indicating that on average, customers were not extremely positive or negative in any of the conditions. To further explore this effect, data of customers’ overall impression was also analyzed per interaction phase.

Figure 14 Visual representation of the observed overall impression of people in different interaction phases (error bars represent 95 % confidence intervals)

7.3.1 Interaction phasesUpon arrival (t(220) = -0.93, p = 0.353) and leaving (t(220) = -0.136, p = 0.892), no significant difference was found between customers’ overall impression in the two light conditions.

During the action of paying for one’s food, a significant difference was found between customers’ overall impression in both light conditions (t(219) = -2.75, p = 0.006). Customers in the warm white light looked more positive overall (M = 3.28, SE = 0.08) compared to customers in the cold white light (M = 2.96, SE = 0.09). The difference in customers’ overall impression was thus mostly due to the more positive overall impression of customers while paying for their food.

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7.4 Communication

7.4.1 ConversationOut of all observed customers, only 31 were seen to make small conversations with the cashier during one phase of the interaction. Although the data showed that in the warm white light, more customers made conversation with the cashier (5.4 %) compared to customers in the cold white light (3.9 %), a chi-square test comparing both light conditions revealed that this difference was not significant (χ2 (1, N = 666) = 0.81, p = 0.464), see Table 16.

7.4.2 Courtesies (greeting, indicating type of payment, saying bye and thanking)For the observations regarding the various courtesies, data was analyzed only for the specific interaction phase in which the courtesy took place (see Table 17).

In the warm white light condition, fewer customers greeted the cashier verbally (56.3 %) compared to customers in the cold white light (67.0 %). More customers in the warm white light however greeted the cashier non-verbally, e.g. by knotting, smiling etc. (8.6 %) compared to customers in the cold white light (5.3 %), see Table 17. A chi-square test however revealed no significant difference between both light conditions (χ2 (2, N=222) = 2.79, p = 0.122).

With regards to whether or not customers indicated they wanted to pay by card (instead of starting the payment without indication), only customers who actually paid by card were taken into account in this analysis. In the warm white light condition, more customers offered an indication to the cashier that they wished to pay by debit card before inserting the card into the cash machine (43.9 %) compared to customers in the cold white light (19.5 %), see Table 17. A chi-square test exploring this comparison indicated that the difference between the light conditions was significant (χ2 (1, N = 98) = 6.33, p = 0.017), indicating that when paying for food, customers were more likely to communicate to the cashier about their payment type in the warm white light condition, partly supporting hypothesis 4.

Also, in the warm white light condition, fewer customers thanked the cashier while leaving verbally (62.2 %) compared to customers in the cold white light condition (67.7 %) and also non-verbally (0 % of customers in the warm white light compared to 1.1 % of customers in the cold white light), see Table 17. However, a chi-square test comparing both groups did not reveal a significant difference between both light conditions (χ2 (2, N=220) = 2.29, p = 0.165).

Table 16 Overview of the results of the chi-square test comparing whether customers made conversations with the cashier in both light conditions


Conversation Warm (n = 386) Cold (n = 280)


Yes 5.4 % n = 21 3.9 % n = 11

No 94.6 % n = 365 96.1 % n = 269

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Last, in the warm white light, more customers said goodbye to the cashier, both verbally (15.9 %) and non-verbally (5.6 %) compared to customers in the cold white light (9.9 % and 2.2 % respectively). See Table 17 for more detailed results. A chi-square test comparing both light conditions indicated a trend (χ2 (2, N=217) = 3.41, p = 0.092). This data again offers support for our hypothesis 4, in that more communication would take place between the customer and the cashier in the warm white light condition.

Table 17 Overview of the results of the chi-square tests comparing the various courtesies in different light conditions


Courtesies Coding Warm Cold


Greeting

Verbally 56.3 % n = 72/128 67.0 % n = 63/94

Non-verbally 8.6 % n = 11/128 5.3 % n = 5/94

Not at all 35.2 % n = 45/128 27.7 % n = 26/94

Indicating payment

Yes 43.9 % n = 25/57 19.5 % n = 8/41

No 56.1 % n = 32/57 80.5 % n = 33/41

Thanking

Verbally 62.2 % n = 79/127 67.7 % n = 63/93

Non-verbally 0 % n = 0/127 1.1 % n = 1/93

Not at all 37.8 % n = 48/127 31.2 % n = 29/93

Saying goodbye

Verbally 15.9 % n = 20/126 9.9 % n = 9/91

Non-verbally 5.6 % n = 7/126 2.2 % n = 2/91

Not at all 78.6 % n = 99/126 87.9 % n = 80/91

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Discussion study 28 In the second study of this project we explored whether color temperature of light (cold vs. warm) would have an effect on people’s social behavior as observed in their social interactions with a cashier. Interactions were measured via four coding categories (facial expression, viewing behavior, overall impression and communication (divided between courtesies and communication) to investigate whether warm white light would elicit more positive interactions and more communication with the cashier.

8.1 The social effect of color temperature of light

Exploring customers’ interactions indicated that their overall impression was more positive in the warm white light condition (e.g. people were nicer, smiled more, were more polite overall etc.), but only while paying at the register. Also, customers’ facial expression was more positive in the warm white light; people smiled more often when arriving at the register and while paying for their food, and people frowned less often during all phases of the interaction in the warm white light compared to in the cold white light. However, some contradicting results were found when analyzing the category viewing behavior; when leaving the register, customers were more likely to make eye contact with the cashier in the cold white light compared to in the warm white light. The same effect was not found in the analyses of the other interaction phases. Taken together, although not all behavior was affected in the same way, the results still offer support for our hypothesis 3 stating that warm white light would elicit more positive interactions than cold white light.

To explore the extent to which customers communicated with the cashier, different types of communication were measured; greetings, indicating the type of payment people wanted to use, saying goodbye, thanking the cashier and actually starting a conversation with the cashier. The results of these observations show that color temperature of light influenced customers’ behavior in the expected way for at least two of the measurements. In the warm white light, a larger percentage of customers said goodbye to the cashier when leaving, both verbally and non-verbally. Moreover, a larger percentage of customers that paid via debit card actually indicated their preferred payment type to the cashier before starting the payment in the warm white light condition (compared to people who started the payment without any indication or communication with the cashier). Although not all observed communication types were seen to be affected by the color temperature of light, these results still offer support for our hypothesis 4, showing that in warm white light customers were more likely to communicate with the cashier in various ways compared to in the cold white light.

Warm white light elicits more positive interactions than cold white light.

Customers communicated with the cashier more often in the warm white light condition.

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8.2 Methodological paradigm

8.2.1 Limitations of the observationsOne explanation for the fact that warm white light did not seem to positively influence all our observation categories could be the type of observations we chose to conduct. Although this type of interaction was chosen since it is quite similar for each customer and it is easy to divide behavior in specific categories, this behavior is also quite consistent overall and might be less affected by other situational cues. Customers were mostly seen to be quite neutral and have probably adapted some sort of behavioral pattern already for these types of social interactions. For future research, it might therefore be interesting to investigate other types of behavior that are more affected by situational cues, or perhaps induce some sort of ‘breach’ into people’s normal social pattern and explore the effects of color temperature of light on their adjusting behavior. This form of observation studies is called ‘breaching experiments’ (Milgram, Liberty, Toledo & Wackenhut, 1986) and usually employs a confederate to intervene in some sort of social behavior after which behavior of other people in the situation is observed to explore the effect of this interruption. This might be another interesting way to investigate whether warm white light could lead to a more positive, or less negative in this case, reaction of people to the actions of the confederate.

Another possible aspect that could have affected our results is the behavior of the cashiers themselves. Although they were not told about the hypothesized effect of the different light conditions, it might be that their own behavior was affected by the light conditions in the same way that customers’ behavior was influenced. In general, the cashiers were seen to behave quite positively and polite towards customers in both light conditions, but because we did not observe their behavior in detail it is not possible to rule out any effects of the light conditions on their behavior completely. However, because the cashiers’ interactions seemed very positive in general, customer’s interactions might also be partially influenced by the interactions of the cashiers in a different way. Baron et al. (1992) showed that the presence of another positive aspect (a gift) nullified the effect of warm white light on positive affect. In other words, if the interactions of the cashiers would have been less positive in general, a larger difference in customers’ interactions might have been visible between the light conditions (e.g. the number of positive interactions in the cold white light might decrease). It would therefore be interesting in future work to be able to also control for the way the cashiers react to the observed subjects themselves to determine whether the effect of warm white light will be more evident when no positive behavior is shown by the cashiers.

8.2.2 Limitations of the light conditionsBecause of the discrepancy between the induced light settings and the original light settings, other aspects of the light conditions might have influenced the observed results. First, the intensity of the original light setting at the observed register was much lower (approximately 100 lux) compared to the induced light setting (200 lux). In both light conditions (warm and cold) the intensity of the light was thus much higher than usual and might have influenced the observed behavior of customers. Moreover, since the original light setting (approximately 3000 K) resembles the warm white light setting more than the cold white light setting, customers might have been more aware of the induced cold white light than they were of the warm white light. This was especially the case because at the other two registers, the original light settings were kept in place (2800-3000 K). The cold white light was thus more clearly different from the original light setting during the observations than the warm white light, perhaps leading customers to adjust behavior more in the cold white light.

Last, in our first experiment we found that people tend to evaluate situations more

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socially in warm white light than in cold white light. In this second study however, the observer was not blind to the experimental conditions. It might therefore be that when customers were observed in the warm white light they were rated more positively and socially because the observer rated the situation as more positive in the warm white light, which was indicated as a possibility in our first study. We tried to minimize these effects by creating coding categories that could objectively measure specific parts of the behavior. However, it might be better for future research to videotape people’s behavior and analyze the data using a color filter in order to reduce the knowledge of each light setting. Due to privacy constrains in this study we chose to observe the behavior of people in real-life.

8.2.3 SummaryTaken together, this study offers new insights into the potential positive mechanism of warm white light (vs. cold white light). We explored behavior in other ways than most other studies (Baron et al., 1992), namely we observed real-life interactions between people. To our knowledge, no studies have been conducted in real-life settings that have tried to investigate the influence of warm white light on actual social behavior. Although not all observations were affected in the same way by the induced light settings, the results of this observation study are still very positive and extend the positive effects of warm white light found in the laboratory (Baron et al., 1992) into real-life situations. Even when other variables and situational cues can play a role, warm white light was still seen to induce more positive and social interactions and is thus seen to positively affect real-life social behavior. More research will be needed however to explore whether this positive effect of warm white light can be found in various other social situations as well.

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General discussion9 This research started off as trying to investigate how interactive lighting could potentially lead to an increase in de-escalating, or a decrease in aggressive, behavior. Because very little prior research has investigated the effects of color temperature of light on behavior, we thought it important to first get a grasp on the way color temperature of light could affect people’s appraisal of and behavior in different situations instead of focusing on aggression specifically. We therefore investigated whether people’s social appraisal of situations was guided by color temperature of light (warm; 2900 K vs. cold; 5800 K) acting as a situational cue (when light was shed on the situation itself) in a first laboratory experiment and whether people’s social interactions were guided by color temperature of light (warm; 2700 K vs. cold; 5600 K) via an observation study in a real-life situation. Both aspects of the effect of color temperature of light had, to our knowledge, not been investigated in previous research.

In the first study, warm white light was seen to significantly affect people’s social appraisal of ambiguous situations. Participants in this study showed a significantly smaller social distance to the people in the pictures in warm white light than in cold white light, based on their written evaluations of the situations, indicating they felt closer to the people in these situations. Importantly, this was only found when the color temperature of light was changed directly in the situation itself (affecting the visual appearance of the situation most) and not when the light was changed around the participant itself. This substantiates that warm white light can indeed act as a situational cue to sociality, when no other such cues are available (e.g. in ambiguous situations).

To further investigate this, in the second study, we explored the effects of color temperature on real-life social behavior, namely social interactions with a cashier when paying for food. Warm white light was seen to positively affect several types of social interactions with a cashier while paying for food. Customers’ facial expression and overall impression was significantly more positive in the warm white light compared to cold white light, and warm white light seemed to increase communication between the customer and the cashier. Although not all observations elicited the same positive influence of warm white light, this observation study shows that warm white light can be beneficial in guiding more positive and social behavior, even when a multitude of other situational cues is available.

In general, this research contributes to the existing research about the positive effect of warm white light on several aspects of inter-personal behavior. With these two experiments, specific aspects of sociality (appraisal and interactions) were explored in order to get a first grasp on the effects of color temperature of light on these social concepts. One issue that arises in crowded environments is the fact that people feel anonymous, which can result in disinhibited, and potentially anti-social, behavior. Although we did not specifically investigate the effect of color temperature on preventing such behavior in this experiment, we do feel that our results offer some indications that warm white light can potentially be beneficial in this regard. First, in our first experiment, it was shown that in warm white light, participants’ social distance towards the people in the environment became smaller, indicating they felt closer to the participants. This effect might counterbalance, to some extent, the anonymity that is induced by crowding in the first place. Second, in this same experiment, it was shown that participants’ social appraisal of the situation was influenced only when the color temperature of light was visible in the situation itself, indicating the potential of color temperature of light acting as a situational cue for these situations. Other

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research has shown that inducing positive situational cues, especially when people are anonymous, can positively affect people’s behavior. People were for example seen to act less aggressively when they were presented with a nurse’s uniform (less shocks were administered to another person compared to when a Ku Klux Klan uniform was present; Johnson & Downing, 1979) or when they were presented with pleasant music styles (Krahé & Bieneck, 2012). This suggests that warm white light, acting as a situational cue, could also affect behavior and reduce aggressive behavior in certain situations, comparable to other positive situational cues. Last, our second experiment showed that more positive social interactions were observed in warm white light conditions, indicating that behavior could become more social in warm white light, which is the opposite of the type of negative behavior induced by crowding. Warm white light could therefore also affect people’s behavior and counterbalance the negative effects of crowding, possibly reducing anti-social behavior (e.g. aggression).

It should be noted that, because of the small amount of research that has already been done in this area, the two experiments were set-up in a rather exploratory manner. Because of this, we also explored some other possible mechanisms (atmosphere perception, the extent to which warm white light acted as a positive distracter and perceived temperature) in the first laboratory study. However, we did not find any evidence that the explored mechanisms could explain the positive effects of warm white light. In the real-life behavior study it was hard to measure or control for other possible mechanisms or confounding factors (e.g. other situational cues), which might also play a role in people’s sociality towards situations. In order to fully understand whether the effect of color temperature of light is guided by any of these factors, research paradigms should be designed to specifically investigate these effects. Nevertheless, we feel that with this study, we succeeded in creating novel research paradigms in order to begin investigating the effects of color temperature of light more thoroughly than was done in previous studies.

Taken together, the exploratory studies presented in this paper indicate that warm white light can have a positive effect on the sociality of people in various situations. First, warm white light can guide people’s social appraisal of social situations in a positive way. Second, and more importantly, besides these results found in a laboratory setting where no other situational cues were induced, our second observation study indicates that this positive effect even persists in real-life situations where a variety of other factors could potentially affect behavior. Warm white light can thus strongly affect people’s social behavior in a positive way, eliciting behavior that is more social in general. Although more research will be needed to fully investigate in what way warm white light could benefit the process of de-escalating behavior and to explore the strength of this effect, we feel that these results already indicate warm white light may be beneficial in many situations were guiding (positive) behavior is wanted or required.

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60

Appendices

Appendix A – Light measurements Lightinglab

The next tables show the data of the various seperate measurements that were taken in the Lightinglab with the original set-up. Measurements were taken in both the participant and the situation part of the room.

Color temperature of light:

Illumination:

61

Appendix B – Physical experiment booklet

Intro Tijdens dit experiment zal je gevraagd worden enkele vragenlijsten in te vullen en een aantal afbeeldingen van situaties tussen verschillende personen te beoordelen. Instructies voor de verschillende taken vind je bij de bijbehorende taak in dit boekje. Mocht je nog vragen hebben gedurende het experiment, stel deze dan hardop. De experimentleider zal hier dan antwoord op geven. Je gaat nu beginnen aan het experiment. Wil je ervoor zorgen dat je telefoon uit of op stil staat?

62

Deel 1 De volgende vragen gaan over hoe jij je voelt op dit moment. Geef van onderstaande termen aan hoe deze term op jou van toepassing is, op dit moment. Denk hierover niet te lang na, het gaat om hoe jij je voelt. Geef antwoord aan de hand van de onderstaande schaal door een kruisje te zetten in het vakje dat het best van toepassing is: Helemaal

niet Nauwelijks Enigszins Behoorlijk Heel erg

Energiek

Ontspannen

Blij

Slaperig

Op je gemak

Nerveus

Kalm

Verdrietig

Alert

Moe

Gespannen

Tevreden

Aandachtig

63

Deel 2 Gedurende dit deel van het experiment zul je een reeks afbeeldingen te zien krijgen. Deze afbeeldingen verschijnen in het venster recht voor je. Laat telkens deze afbeelding even op je inwerken voordat je doorgaat. Schrijf voor elke afbeelding op wat er volgens jou gebeurt en hoe de personen op de afbeelding zich voelen. Beschrijf dit in drie zinnen. Denk hierover niet te lang na; er zijn geen goede of foute antwoorden, het gaat om jouw eigen indruk. LET OP: na het opschrijven van je indruk over iedere afbeelding is het belangrijk dat je op het belletje naast je drukt. Hierna zal er een nieuwe afbeelding verschijnen. Ook zal telkens de licht conditie in de ruimte veranderen. Wanneer de nieuwe afbeelding te zien is kun je doorgaan met de volgende pagina van dit boekje. Druk nu op het belletje en ga door naar de volgende pagina.

64

Afbeelding 1 (2, 3, 4, 5, 6, 7, 8) Schrijf in drie zinnen op wat er volgens jou gebeurt en hoe de personen op de afbeelding zich voelen. Denk hierover niet te lang na; er zijn geen goede of foute antwoorden, het gaat om jouw eigen eerste indruk. ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ ................................................................................................................................ Druk, wanneer je klaar bent, op het belletje rechts van je. Er zal dan een nieuwe afbeelding verschijnen. Wanneer deze afbeelding in beeld is kun je doorgaan naar de volgende blad.

65

Deel 3 Laat het licht in de ruimte enkele ogenblikken op je inwerken. Geef bij de onderstaande termen en stellingen aan in welke mate jij vindt dat de term/stelling van toepassing is op de sfeer in de ruimte waarin nu het witte vlak te zien is (laat de ruimte waarin jij je bevindt buiten beschouwing). Geef antwoord aan de hand van de onderstaande schaal door een kruisje te zetten in het vakje dat het best van toepassing is:

Helemaal niet Nauwelijks Enigszins Behoorlijk Zeer

goed

Knus

Levendig

Gespannen

Beangstigend

Zakelijk

Intiem

Stimulerend

Formeel

Gezellig

Bedreigend

Koud

Geborgen

Vrolijk

Kil

Beklemmend

Inspirerend

Warm

Helemaal niet Nauwelijks Enigszins Behoorlijk Heel

erg De verlichting in de ruimte met het witte vlak vind ik storend.

De verlichting in de ruimte met het witte vlak leidt me af.

De verlichting in de ruimte met het witte vlak geeft me een positieve afleiding.

Hoe zou je de temperatuur in de ruimte waarin het witte vlak te zien is beschrijven? (zet een kruisje in het bijbehorende vakje) Koud Warm

66

DEEL 4 Nu volgen een aantal algemene vragen over jou als persoon. Druk nogmaals op het belletje, het licht zal nu nog een laatste keer veranderen. Geef aan welke uitspraken op jou van toepassing zijn (dat wil zeggen, in welke mate beschrijft elke uitspraak jou als een persoon). Denk hierover niet te lang na. Geef antwoord aan de hand van de onderstaande schaal door een kruisje te zetten in het vakje dat het best van toepassing is:

Sterk mee

oneens Oneens Geen

mening Eens Sterk mee eens

Als andere mensen me niet aanvaarden, dan heb ik daar geen last van.

Ik doe heel erg mijn best om dingen te vermijden waardoor anderen mij zouden vermijden of uitsluiten.

Ik ben zelden bezorgd of andere mensen om me geven of niet.

Ik moet het gevoel hebben dat er andere personen zijn waar ik naartoe kan als ik problemen heb.

Ik wil dat andere mensen me aanvaarden.

Ik hou er niet van om alleen te zijn.

Ik heb er geen last van als ik gescheiden ben van mijn vrienden voor een lange periode.

Ik heb een sterke behoefte om ergens bij te horen.

Ik heb het er moeilijk mee als ik niet betrokken ben bij de plannen van anderen.

Ik voel me snel slecht wanneer ik weet dat anderen me niet aanvaarden.

Ga door op de volgende pagina.

67

Geef weer aan welke uitspraken op jou van toepassing zijn (dat wil zeggen, in welke mate beschrijft elke uitspraak jou als een persoon). Denk hierover niet te lang na. Geef antwoord aan de hand van de onderstaande schaal door een kruisje te zetten in het vakje dat het best van toepassing is op jou:

Sterk mee

oneens Oneens Geen

mening Eens Sterk mee eens

Verdriet probeer ik zelf te verwerken.

Emotionele problemen houd ik liever voor me.

Ik vind het beter om me emotioneel in te houden.

Gevoelens zijn mijn eigen zaak.

Als ik met iets zit stap ik graag naar iemand toe.

Ik wil met anderen praten over wat ik voel, wat ik innerlijk meemaak.

Ik kijk wel uit anderen te vertellen dat ik problemen heb.

Juist wanneer ik het moeilijk heb wil ik graag tegen iemand aanleunen.

Ik vind het vervelend raad te moeten vragen.

Ik wil mijn gevoelsleven delen.

Als ik in moeilijkheden zit heb ik behoefte aan hulp en steun van anderen.

Op de volgende, laatste, pagina volgen nog een paar vragen over jou en je beleving van het experiment.

68

Deel 5 Wat is je leeftijd? ....... Wat is je geslacht? Man/vrouw Gedurende het experiment veranderde het licht een aantal keren. Op welke manier heb jij het licht zien veranderen? (Omcirkel jouw antwoord) Het licht veranderde alleen in de ruimte waarin ik me bevond

Het licht veranderde alleen in ruimte waarin de afbeeldingen zich bevonden

Het licht veranderde in beide ruimtes

Wat veranderde er volgens jou aan het licht? ....................................................................................................................................... ....................................................................................................................................... Herkende je een van de mensen op onderstaande afbeeldingen? Omcirkel dan deze persoon hieronder en geef aan waar je deze persoon of personen van (her)kent.

69

Appendix C - Overview of complete picture set

Appendix D – Overview measurements for different pictures (light and color measurements)

The following table shows measurements taken of the various pictures via the program Photoshop to assess the colors in the pictures, and via the program ImageJ to assess the light levels in each picture.

70

Appendix E – Form of consent

Informed consent“Situaties Evalueren” - 2013

In dit experiment vragen we je om een aantal vragenlijsten in te vullen en daarnaast een aantal afbeeldingen van diverse situaties te beoordelen. Alle data in dit experiment zal vertrouwelijk worden behandeld en anoniem worden gerapporteerd.

Wanneer je bezwaren hebt tegen het delen van deze informatie kun je helaas niet meedoen met dit experiment.

De resultaten worden alleen gebruikt voor wetenschappelijk onderzoek in dit project. Wanneer je om wat voor reden wilt stoppen met het experiment, kun je dit aangeven op ieder punt in het experiment.

Wanneer je nog vragen hebt, stel deze dan gerust.

Vul je naam en handtekening hieronder in wanneer je mee wilt doen met het experiment:

Datum: __________________ Naam: ________________________________

Handtekening: ________________________________

71

Appendix F – Protocol

Protocol experiment

Voorbereiding- foto’s op goede volgorde leggen/zetten- lichtconditie checken- formulieren vervangen

Introductie- participant meenemen naar tafel- form of consent invullen- in studie foto’s beoordelen, vragenlijsten, video opnames etc.- instructieblad uitleggen, hier alles op invullen, wordt alles op uitgelegd- foto’s beoordelen, verschijnen in ruimte zichtbaar door gat (op wijzen), uitleg foto’s beoordelen: schrijf in drie zinnen op wat er volgens jou gebeurd en hoe de personen op de afbeelding zich voelen- probeer iedere foto op zichzelf te beoordelen, iedere foto is een aparte situatie en heeft niets met de andere situaties te maken- als klaar met schrijven, duw op bel naast je, de volgende foto verschijnt dan- ook lichtcondities veranderen iedere keer- als vragen tijdens test, gewoon hardop stellen, experiment leider kan je horen (zit in ruimte hiernaast)- je mag beginnen zodra het vlak dat je ziet is afgeschermd met een wit vlak- wanneer je klaar bent, zeg dit dan hardop en de experiment leider zal je komen halen

Begin test- je mag nu beginnen met de eerste vragenlijst, succes- zelf in andere ruimte gaan zitten, lichtconditie checken

72

Appendix G – Light measurements cafeteria

The next tables shos the data of the various seperate measurements that were taken in the cafeteria from different view-points (measured viewing the register and viewing the luminaire) in both lighting conditions. The first table indicates different points of measurement for the illuminance and colour temperature of the light. The second table indicates different points of measurement for the luminance of the light.

Warm white light

Point of measurement (see image)1 (center) 5.364 * 10^3

1 5.841 * 10^31 5.328 * 10^31 4.942 * 10^31 5.196 * 10^3

Average 5.3342 * 10^32 1.429 * 10^33 4.165 * 10^34 3.978 * 10^35 4.379 * 10^3

Average value: 3.85704 * 10^3 cd/m^2

Cold white light

Point of measurement (see image)1 (center) 4.447 * 10^3

1 4.161 * 10^31 5.418 * 10^31 5.492 * 10^31 5.301 * 10^3

Average 4.9638 * 10^32 1.597 * 10^33 3.965 * 10^34 3.671 * 10^35 4.422 * 10^3

Average value: 3.72376 * 10^3 cd/m^2

12 3

4

5

Different measurement points on the front side of the lamp (luminance)

73

Appendix H – Coding scheme for the observation study

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