Transportation Research Part F 21 (2013) 43–51

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Transportation Research Part F

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Assessing individual differences in driving inattention:Adaptation and validation of the Attention-RelatedDriving Errors Scale to Spain

1369-8478/$ - see front matter � 2013 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.trf.2013.09.001

⇑ Corresponding author at: Departamento de Psicología Experimental, Facultad de Psicología, Universidad de Granada, Campus Universitario Car18071 Granada, Spain. Tel.: +34 958 240 663; fax: +34 958 246 239.

E-mail addresses: jroca@ugr.es (J. Roca), jpadilla@ugr.es (J.-L. Padilla), mariafernandalopezramon@gmail.com (M.-F. López-Ramón), candid(C. Castro).

Javier Roca a,b,⇑, José-Luis Padilla c, María-Fernanda López-Ramón a,d, Cándida Castro a

a Departamento de Psicología Experimental, Facultad de Psicología, Universidad de Granada, Campus Universitario Cartuja, s/n, 18071 Granada, Spainb Departamento de Psicología Evolutiva y de la Educación, Universidad de Valencia, Avenida Blasco Ibáñez, 21, 46010 Valencia, Spainc Departamento de Metodología de las Ciencias del Comportamiento, Facultad de Psicología, Universidad de Granada, Campus Universitario Cartuja, s/n, 18071Granada, Spaind Centro de Investigación en Procesos Básicos, Metodología y Educación, CONICET, Mar del Plata, Argentina

a r t i c l e i n f o

Article history:Received 4 August 2012Received in revised form 25 April 2013Accepted 4 September 2013

Keywords:Attentional errorsDriver inattentionAttention-Related Driving Errors ScaleQuestionnaire adaptationDriver behaviourRoad safety

a b s t r a c t

The Attention-Related Driving Errors Scale (ARDES) is a self-reported questionnaire toassess individual differences in the proneness to make attentional errors while driving.The aims of the current work are to adapt the original Argentinean version of the ARDESto the culture, language, traffic regulations and driving habits of Spain and provide newvalidity evidence of the cross-cultural equivalence of the scale. In the first step of the val-idation process, five external independent experts reviewed the original ARDES-Argentinaand proposed modifications, adapted to the culture, language, traffic regulations and driv-ing habits in Spain. Secondly, a sample of 320 drivers completed the adapted questionnaire.Descriptive statistics and psychometric properties (corrected item-total correlation, Cron-bach’s alpha and factor structure) were performed on the data. Besides, in order to obtainfurther validity evidence, the relationships between the questionnaire scores and socio-demographic variables (age, sex, educational level, driving experience, crash involvementand traffic fines received) were analyzed. Factor analysis suggested a single factor thatexceeded the parallel analysis criterion and accounted for 32.70% of the total variance.All items showed positive loadings on this factor, ranging from .41 to .72. The correcteditem-total correlation values extend from .41 to .60, indicating that the items had good dis-crimination power. Cronbach’s alpha coefficient value was .88. The analysis of the relation-ships between ARDES-Spain scores and socio-demographic variables provided furthervalidity evidence of the appropriateness of the adapted questionnaire. In particular, differ-ences in ARDES-Spain scores were found between drivers who reported traffic collisionswith material damage and participants who did not. In conclusion, results in the currentstudy suggest that the adapted version of the ARDES is a useful tool for evaluating theproneness to attentional errors during driving in the Spanish population. Future studiesadapting the questionnaire to other countries with different languages, cultures, traffic reg-ulations and driving habits are encouraged in order to expand the discussion on the cross-cultural equivalence of the ARDES.

� 2013 Elsevier Ltd. All rights reserved.

tuja, s/n,

a@ugr.es

44 J. Roca et al. / Transportation Research Part F 21 (2013) 43–51

1. Introduction

Current research in road traffic domain shows that driver inattention is one of the main factors explaining accidents andits negative influence on safety is expected to further increase, as a consequence of the proliferation of some potentially dis-tractive in-vehicle technologies (e.g., Klauer, Dingus, Neale, Sudweeks, & Ramsey, 2006; Ranney, 2008; Stutts, Reinfurt, Sta-plin, & Rodgman, 2001). Multiple research strategies, including controlled experiments in a laboratory or in drivingsimulators, test track and field studies and also correlation analyses of questionnaire data, are complementary being appliedto better understand driver inattention and thus prevent attention-related accidents (for a review see, for example, Kircher,2007).

According to a recent review (Regan, Hallett, & Gordon, 2011), driver inattention can be defined as ‘‘insufficient or no atten-tion to activities critical for safe driving’’ (pp. 1775). In addition, Regan et al. (2011) proposed a taxonomy in which the differ-ent categories of inattention are distinguished by the different mechanisms that produce driver inattention. For example,among these categories, driver distraction is considered as ‘‘the diversion of attention away from activities critical for safe driv-ing toward a competing activity’’ (Regan et al., 2011, pp. 1776), whereas other forms of driving inattention do not require acompeting activity (e.g., when the driver is influenced by biological factors that physically prevent the detection of criticalinformation, such as micro-sleeps).

Ledesma, Montes, Poó, and López-Ramón (2010) suggested that individual differences in driver inattention might reflect arelatively stable pattern of behaviour associated with attentional errors in different dimensions of everyday life and withparticular psychological variables. Accordingly, those individuals who are more prone to make attentional errors while driv-ing will also manifest inattention in their daily lives and will present specific psychological traits (Ledesma et al., 2010).Within this theoretical framework, the Attention-Related Driving Errors Scale (ARDES; Ledesma et al., 2010) was developedto assess individual differences in the proneness to driving inattention. Whereas Regan et al. (2011)’s taxonomy was focusedon the mechanisms that produce driver inattention (i.e. the different sources of inattention, such as a micro-sleep or a distrac-tion), the work by Ledesma et al. (2010) was aimed at measuring the resulting errors (i.e., the consequences of inattention, suchas failing to spot a pedestrian crossing or to notice a leading vehicle slowing down, which can be brought by several of theinattention sources defined in Regan et al.’s taxonomy; see also Stutts et al., 2001). In this regard, a number of attention-re-lated driving errors were used as indicators to measure the construct of driver inattention (particularly, the proneness todriver inattention) by means of the ARDES.

1.1. The Attention-Related Driving Errors Scale (ARDES)

The items in the ARDES, originally developed for Argentinean culture, language, traffic regulations and driving habits, spe-cifically refer to non-deliberate errors in driving performance resulting from an attentional failure, such as failing to notice apedestrian crossing the street (Ledesma et al., 2010). Items and instructions were based on previous questionnaires, such asthe Attentional Lapses subscale of the Driver Behaviour Questionnaire (DBQ; Reason, Manstead, Stradling, Baxter, & Camp-bell, 1990), and the Multidimensional Driving Style Inventory (MDSI; Taubman-Ben-Ari, Mikulincer, & Gillath, 2004). How-ever, according to Ledesma et al. (2010), in comparison with these questionnaires, the ARDES was specifically developed tomeasure driving attentional errors and avoid overlapping with other psychological constructs such as planning errors, whichare not attentional in nature, or daydreaming, what is not essentially an error (actually, in Regan et al.’s, 2011, taxonomy,daydreaming is considered as a source of inattention that might lead to driving errors, and thus it is not an error per se). Be-sides, the internal consistency of the original Argentinean version of the ARDES has been reported to be higher than theAttentional Lapses subscale of the DBQ, and it covers a wider range of inattentive driving behaviour than the latter (see Led-esma et al., 2010). In consequence, the ARDES may constitute a promising tool available to researchers interested in analys-ing driver inattention.

Reliability and validity of the scores obtained from the original Argentinean version of the ARDES were evaluated on asample of drivers in Argentine (Ledesma et al., 2010). An exploratory factor analysis suggested that all 19 items in the scaleare multiple indicators of a one-dimensional construct related to the proneness to attention-related errors while driving(high loadings on the first factor and good discrimination indexes were observed; internal consistency was also high, Cron-bach’s alpha = .86). The one-dimensional factor solution was consistent with previous studies with related questionnaires,such as the Driver Behaviour Questionnaire (DBQ; Reason et al., 1990) and the Multidimensional Driving Style Inventory(MDSI; Taubman-Ben-Ari et al., 2004), in which a single inattentive driving factor was differentiated from other dimensionsof driver behaviour. First, Reason et al. (1990) developed the DBQ to distinguish between non-intentional driving errors anddeliberate traffic violations, supporting the idea that different psychological processes influence these factors. In their origi-nal study, a factor analysis provided support for the difference between errors and violations and, additionally, evidence wasfound of a third factor that mainly included minor attentional failures (‘‘slips and lapses’’ or simply ‘‘lapses’’). On the otherhand, Taubman-Ben-Ari et al. (2004) developed the MDSI as a multidimensional instrument to evaluate eight driving styles(dissociative, anxious, risky, angry, high-velocity, distress reduction, patient and careful). Among them, the dissociative stylewas characterized as a tendency to get distracted easily, commit errors due to distractions and exhibit cognitive failures andexperiences of dissociation during driving that could modulate inattention errors.

J. Roca et al. / Transportation Research Part F 21 (2013) 43–51 45

The relationship between the scores obtained from the original Argentinean version of the ARDES and a variety of cog-nitive and psychological variables was analysed to provide further validity evidence. First, Ledesma et al. (2010) found a sig-nificant and theoretically consistent pattern of correlations between the ARDES and different measures of cognitive errorproneness (the Attention-Related Cognitive Errors Scale or ARCES, and the Memory Failures Scale or MFS; Cheyne, Carriere,& Smilek, 2006), lack of general awareness and attention (the Mindful-Attention Awareness Scale or MAAS; Brown & Ryan,2003), proneness to boredom (the Boredom Proneness Scale or BPS; Farmer & Sundberg, 1986) and dissociative personalitytraits (the Dissociative Experiences Scale or DES; Bernstein & Putnam, 1986). Second, López-Ramón, Castro, Roca, Ledesma,and Lupiáñez (2011) compared ARDES scores and drivers’ attentional performance in a neurocognitive attentional test (theAttention Networks Test or ANT; Fan, McCandliss, Sommer, Raz, & Posner, 2002) and observed that drivers reporting thegreatest propensity to experience attention-related errors (i.e., higher ARDES scores) showed an overall slowdown in atten-tional performance, less endogenous preparation for high-priority alerting signals and a better response to cognitive conflictin the presence of valid orienting cues. Third, a recent study (López-Ramón et al., in preparation) evaluated a sample of taxidrivers’ attentional performance using the Attention Networks Test for Interactions and Vigilance (ANTI-V; Roca, Castro,López-Ramón, & Lupiáñez, 2011) and found that only the drivers with low propensity to make attentional errors (i.e., lowARDES scores) were able to maintain good attentional functioning after a 12-h working shift (i.e., an alerting tone was moreeffective to reduce cognitive interference). In addition, further evidence of the ARDES validity was provided by exploring therelationship between the drivers’ scores and self-reported crashes and traffic fines (Ledesma et al., 2010). Results showedthat ARDES scores were able to discriminate drivers who reported having been involved in at least one traffic collision withmaterial damage or have had traffic fines.

1.2. Measuring drivers’ proneness to attentional error in different populations

Overall, evidence on the validity and reliability of the original Argentinean version of the ARDES suggests that the scalehas good psychometric properties and thus can be considered as a simple and useful measure of individual differences toattention-related driving errors. However, the cross-cultural stability and applicability of the scale is still uncertain. Onlythe original version of the ARDES has so far been developed and validated, using Argentinean samples, and previous expe-rience with similar questionnaires highlights the importance of developing different versions specifically adapted to thevarying cultures, languages, traffic regulations and driving habits of target populations (for example, see Lajunen, Parker,& Summala, 2004, for a cross-cultural study on the DBQ). Considerations of driving context, language and culture are allhighly relevant when adapting a questionnaire. According to the guidelines of the International Test Commission (Interna-tional Test Commission (ITC), 2010), questionnaire developers should fully take into account the linguistic and cultural dif-ferences among the populations for whom the adapted versions are intended, and should demonstrate that the languageused is appropriate for the populations being tested, as language use can reflect major cultural differences (Hambleton,2001; Van de Vijver & Tanzer, 2004).

The International Test Commission on Adapting Tests (ITC, 2010), reflect the widest consensus among professionals andresearchers about best practices to adapt tests and questionnaires. The ITC guidelines D8 recommends researchers and pub-lishers to provide information on the evaluation of validity in all target populations for whom the adapted versions are in-tended. Language and cultural differences can be frequently found across countries or contexts in which majority languageas English or Spanish are spoken. Spanish is the official language in 21 countries and is used by more than 450 million people.This diversity does not prevent the understanding but causes differences in pragmatic meanings reflecting different tradi-tions, social norms and values. Also, it is possible that the psychological construct measured by ARDES was better assessedby different driving behaviour or alternative traffic situations in either cultural context.

Several indicators in traffic and road safety domains reveal clear differences between Argentina and Spain, and thus not onlythe culture and language but also the traffic regulations and driving habits where the ARDES will be applied would not be di-rectly comparable. For example, according to a recent international study (International Traffic Safety Data, 2012), the absolutenumber of deaths in road traffic accidents is higher in Argentina (5094) than in Spain (2478). Similarly, when differences in pop-ulation sizes are considered, the death rate per 100,000 inhabitants is also superior in Argentina (12.6), as compared to Spain(5.4), and analogous results concerning the death rate per 10,000 vehicles are reported (2.9 vs. 0.8, respectively). Regardingattention-related traffic accidents, it has been estimated that driver distraction is a concurrent factor in at least 39% of crashesin Spain (Instituto OPINA, 2011). There is no official figure for this traffic aspect in Argentina, and thus a comparison is difficult.However, some data suggest, for instance, that cellular phone use might be higher in the latter country. According to an obser-vational study carried out in Argentina (Agencia Nacional de Seguridad Vial, 2011), 7.4% of drivers were using their cellularwhile driving. A similar study in Spain (CONSULTRANS, 2008) found that this figure was 2.6% of drivers. It should be noted thatdifferences between both studies (e.g., different observational protocols) discourage direct comparison between the figures oncellular phone use. For this reason, it is important to create, validate and adapt assessment tools based on participants’ behav-iour and responses to the varying contexts, such as it has been currently done with the ARDES.

1.3. Objectives and practical significance

The differences existing between Argentina and Spain challenge that the same questionnaire (e.g., using the same word-ing or asking about the same behaviours and traffic situations), would obtain similar psychometric properties or a similar

46 J. Roca et al. / Transportation Research Part F 21 (2013) 43–51

factor structure. Thus, differences between the Argentinean and the Spanish culture, language, traffic regulations and drivinghabits, along with the well-known lack of sample invariance of the psychometrics based on the Classical Test Theory (Crock-er & Algina, 1986), suggest further psychometric analyses to confirm that ARDES is also appropriate in Spain. The currentstudy is aimed at adapting the original Argentinean version of the ARDES (ARDES-Argentina) to the culture, language, trafficregulations and driving habits in Spain, thus providing new evidence of the cross-cultural stability and applicability of thescale. Besides, analysing relationships between the Spanish version of the ARDES (ARDES-Spain) and self-reported accidentsand other socio-demographic variables will be of further interest in the current study.

The development of valid, reliable and usable self-reported questionnaires to measure the proneness to attention-relatederrors while driving can be found of interest in different applied research areas. For example, population reference valuescould be obtained and then drivers’ scores may be used to assess individual differences in the proneness to inattention. Next,provided that this construct was effectively related to proper driver performance and accident risk indicators, questionnairescores might be potentially applicable as a part of driver selection processes or as a screening tool to apply customized inter-vention programmes (see, for example, Knipling, Burks, Starner, Thorne, & Barnes, 2011).

Similarly, the proneness to inattention between particular groups of drivers (e.g., novice or older drivers, long haul driv-ers, drivers under the influence of specific drugs or diseases, etc.) could be compared. Therefore the questionnaire might beuseful to better characterize and consequently intervene on vulnerable groups, for instance, making these drivers aware oftheir increased proneness to distraction, identifying the potentially distracting activities that they initiate (which activitiesand when they are performed) and applying interventions that focus on strategic decisions and planning (see, for example,Horrey & Lesch, 2009).

In addition, having versions of the questionnaire adapted to different countries or cultural contexts might allow carryingout cross-cultural comparison studies, discussing potential explanations for the observed differences and providing usefulinformation to be considered by road-safety practitioners (see, for example, Warner, Özkan, Lajunen, & Tzamalouka,2011). In this regard, self-reported questionnaires can be useful tools for researchers and practitioners to draw up or evaluateroad safety interventions.

2. Methods

2.1. Participants

A sample of 320 drivers was recruited to participate in this study. All of them had to fulfil the following inclusion criteria:(a) 18 or more years, (b) in possession of a valid Spanish driving licence for standard cars (i.e. a class B licence, which allowsto drive motor vehicles under 3.5 t and 8 passengers plus the driver), and (c) a driving frequency of at least once a monthduring the last three months. The age of the participants ranged from 18 to 77 years (mean = 39.79, St. Dev. = 11.86),22.50% of them being young drivers (18–29), 63.75% middle-aged (30–54), and 13.75% older than 54 years. Most participantswere men (62.50%), and drove daily (71.56%) or at least once a week (19.68%). The average experience was of 19.17 years (St.Dev. = 11.06) since obtaining the driving licence.

2.2. Instruments

A culturally adapted version of the Attention-Related Driving Errors Scale (ARDES, Ledesma et al., 2010) was developed toassess individual differences in the proneness to make attentional errors while driving in Spain. The modified version was anadaptation of the original scale (ARDES-Argentina) to the culture, language, traffic regulations and driving habits in Spain(ARDES-Spain). The target version of the questionnaire (see Table 1) consists of a set of 19 items and a 5-point Likert-typeresponse scale. The participants were asked to read each item and indicate the frequency that they found themselves as driv-ers in the described situations, ranging from (1) ‘‘never or almost never’’ to (5) ‘‘always or almost always’’.

To obtain the target version of the ARDES-Spain, five external independent experts were asked to evaluate the sourceARDES-Argentina (originally in Rioplatense or River Plate Spanish) and to suggest appropriate adaptations of the item con-tents, instructions and response scale, according to the language spoken in Spain (European Spanish) and also to the differ-ences in the culture, traffic regulations and driving habits. The experts were teachers and/or researchers in the domain oftraffic safety and worked at different Spanish universities. Most had a PhD. Four of them were traffic psychologists andthe one remaining was a mechanical engineer. Some of them were specialised in the research of attentional factors whiledriving. At least one of them had previous experience with questionnaire development. The experts, located in different re-gions of Spain, were provided with a dossier to evaluate individually the 19 items of the source questionnaire, as well as theinstructions and the response scale. For each item, they had to assess whether the proposed text was appropriate to the cul-tural, language and driving context in Spain, using a Likert-type scale from (1) ‘‘Not appropriate at all’’ to (5) ‘‘Very appropri-ate’’. When their answers were 4 or less points, they had also to identify the inappropriate words or expressions, to statebriefly the reasons for their judgement, and finally to propose suitable alternatives. Then, the final wording of the targetitems, instructions and scale was obtained by using the information in the experts’ dossiers. Table 2 shows mean and stan-dard deviation values of the experts’ evaluations of the ARDES-Spain. The majority of the items (14) plus the instructions re-ceived a mean value of 4 points or below and thus, according to the experts, required modifications to be properly understood

Table 1Instructions and items used in the adaptation of the Attention-Related Driving Errors Scale in Spain (ARDES-Spain). As the questionnaire is originally in Spanish,an approximate English translation is provided below (in cursive letters).

INSTRUCCIONES: A continuación se describen situaciones que pueden pasarle a una persona sin querer o sin intención mientras conduce su vehículo.Le pedimos que indique en qué medida estas cosas le pasan a Vd. como conductor. Utilice la siguiente escala: (1) Nunca o casi nunca, (2) Pocas veces,(3) Algunas veces, (4) Muchas veces, (5) Siempre o casi siempre. Marque el número que corresponda con su respuesta en cada situación.INSTRUCTIONS: The following describe situations that can happen unintentionally while a person is driving a vehicle. We ask you to indicate to what extentthese things happen to you as a driver. Use the following scale: (1) Never or hardly ever, (2) Rarely, (3) Sometimes, (4) Often, (5) Always or nearly always. Toanswer, mark the number that fits your response in each situation.

1 Ir hacia un lugar conocido y, por distracción, pasarme algunas calles.Heading towards a known place, becoming distracted, and then going several streets beyond it.

2 Anunciar una maniobra y, sin querer, hacer otra (por ejemplo, poner el intermitente para un lado y girar hacia el otro).Signalling a manoeuvre, but unintentionally making another one (for example, switching on the indicator to turn one way but instead turning the other).

3 Al llegar a una intersección, por estar distraído, no ver un coche que está llegando al cruce.Being distracted when reaching a junction, and as a result failing to see a car approaching the crossroads.

4 De pronto, darme cuenta de que me he perdido o me he equivocado de camino en un trayecto que conozco.Suddenly realising that I’m lost or that I’ve taken the wrong road on a familiar route.

5 Al llegar a una intersección, en lugar de mirar hacia dónde viene el tráfico, mirar hacia el otro lado.When arriving at a junction, instead of looking in the direction that the traffic is coming from, looking the other way.

6 Al llegar a una intersección, no darme cuenta de que un peatón está cruzando la calle.On arriving at a junction, not realising that a pedestrian is crossing the street.

7 No darme cuenta de que hay un objeto o un coche detrás del mío y darle un golpe sin querer.Not realising there is an object or a car behind me and hitting it unintentionally.

8 No darme cuenta de que el vehículo de delante ha reducido su velocidad y tener que frenar bruscamente para evitar un choque.Not realising that the vehicle in front has slowed down and having to brake sharply to avoid a collision.

9 Otro conductor toca el claxon porque me distraigo y no veo que el semáforo ha cambiado a verde.Another driver sounding their horn because I’m distracted and haven’t noticed that the traffic lights have changed to green.

10 Olvidar que llevo las luces largas hasta que otro conductor me da ráfagas advirtiéndome de ello.Forgetting my lights are on full beam until another driver flashes their lights to warn me.

11 Por un breve instante, olvidar hacia dónde estoy conduciendo.Forgetting for a brief moment where I’m driving to.

12 Dar más vueltas de las necesarias para llegar a un lugar al que sé ir.Taking a longer route than necessary to arrive at a place I know how to get to.

13 Por seguir el tráfico, cruzar sin darme cuenta un semáforo que acaba de cambiar a rojo.Going through traffic lights when they’ve just turned red, not realising they had changed because I was following other traffic.

14 Querer arrancar y darme cuenta de que no puse ‘primera’.Trying to drive off and realising I’m not in first gear.

15 Querer utilizar un dispositivo del coche y en su lugar utilizar otro (por ejemplo, querer encender el limpiaparabrisas y en su lugar encender lasluces).Intending to use one device, but using another instead (for example, meaning to switch on the windscreen wipers and instead switching on the lights).

16 Salir hacia un destino y, de pronto, darme cuenta de que estoy yendo hacia otro lado.Leaving for one destination and suddenly realising I’m going in another direction.

17 Por ir distraído, darme cuenta de que ni siquiera he visto el semáforo.Realising that due to distraction, I haven’t even noticed the traffic lights.

18 Sin querer, girar en el lugar equivocado o meterme en dirección contraria.Unintentionally turning in the wrong place or going in the wrong direction.

19 Sin querer, hacer mal un cambio de marcha o meter la marcha inadecuada.Unintentionally crunching the gears or going into an unsuitable gear.

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by drivers in Spain. For instance, items 1 and 2 received the lowest mean values (1.60 and 2.20, respectively) and all the ex-perts suggested substituting words like ‘‘cuadras’’, ‘‘guiño’’ or ‘‘doblar’’ for alternative terms, such as ‘‘calles’’, ‘‘intermitente’’ or‘‘girar). In addition, 5 items plus the response scale obtained a mean value higher than 4 points. Still, when the experts sug-gested alternative wordings, they were also considered for modification. The reviewers generally agreed on the identificationof the inappropriate words or expressions and also in the alternatives proposed. However, when there were different judg-ments, the rule of the majority was used to select the most appropriate alternatives.

Next, an electronic version of the questionnaire was programmed using LimeSurvey software (i.e., an open source appli-cation to carry out survey studies; see http://www.limesurvey.org for further information). This software controlled thequestionnaire presentation and response collection in three tablets PC. Special care was taken to assure that the graphicaldisplay, the tactile screen, and the software configurations were the same in the three computers. Also, the tablets PC ranthe survey off-line (they were not connected to any on-line server). Since the source ARDES-Argentina was originally vali-dated using paper-and-pencil administration, the design of the tablet PC version of the target ARDES-Spain questionnairetried to emulate paper-and-pencil presentation (for example, the participants were shown a fixed sequence of screensand they had to use a pen to mark their responses on the tactile screen) to reduce the influence of a potential administrationmethod bias. When completing the questionnaire, the first screen thanked the participants for their interest and gave themgeneral information (e.g., on funding institutions and on the anonymity of the study). The second screen presented specificinstructions for the ARDES-Spain questionnaire (see Table 1). The following three screens showed the questions in sets (5–7questions per set) and the participants had to mark each answer by pressing the pen against the corresponding number. The

Table 2Summary of the experts’ evaluation of the ARDES-Argentina. Mean and standarddeviation (St. Dev.) are shown for each of the 19 items plus the instructions and theresponse scale.

Item Mean St. Dev.

1 2.20 0.842 1.60 0.553 3.80 0.844 3.20 1.305 3.60 0.896 4.20 0.457 3.25 0.968 4.00 1.229 4.00 0.7110 3.40 1.3411 2.80 0.8412 4.40 0.8913 3.40 0.8914 4.60 0.5515 4.80 0.4516 4.80 0.4517 2.20 0.4518 4.00 1.2219 2.60 0.89Instructions 2.80 0.84Response scale 2.20 0.84

48 J. Roca et al. / Transportation Research Part F 21 (2013) 43–51

order of the items was the same for all the participants, and it was coincident to the original ARDES-Argentina. The partic-ipants also completed a second questionnaire, whose main objective was different to the adaptation of the ARDES question-naire and will be discussed elsewhere. The presentation order of these two questionnaires was counter-balanced. Next, aseries of screens asked the participants to give some socio-demographic information (i.e., age, sex, educational level, drivingexperience, crash involvement as a driver for last 12 months, etc.). Finally, a last screen thanked the participants for theirparticipation.

2.3. Procedure

The survey was initially tested using 8 participants, and some minor corrections were made (e.g., text spelling). Theseparticipants were excluded from final data analyses. Then, three interviewers were recruited to participate in the fieldwork.A specific training session was performed to give administration guidelines and also to make them familiar with the objec-tives of the study, the use of the tablet PC, and the application of the electronic questionnaire. The three interviewers weretaking a Master degree at the School of Psychology of the University of Granada, and received a compensation for their col-laboration in this research. The fieldwork took place from 16th February to 4th March 2011. Participants were contactedwhile waiting in the Federico García Lorca Granada-Jaén Airport or in the Granada Train Station. Proper authorizations wereobtained to carry out the study in these locations. The interviewers approached potential participants, described main objec-tives of the study, and asked for their agreement and consent to participate. Then, they checked the fulfilment of the inclu-sion criteria (as specified in Section 2.1). Finally, the participants were shown the use of the tablet PC and filled in thequestionnaire by themselves. On average, the questionnaire required 9 min to be completed. No financial compensationwas offered for taking part in the study.

2.4. Data analyses

Statistical analyses were performed using SPSS v15 for Windows. First, data were inspected for missing, extreme, andincoherent values. The items of the ARDES-Spain scale were free of missing values, since a valid answer was required to con-tinue and complete the questionnaire. Regarding the socio-demographic information and control variables, only a few miss-ing or extreme values were found (for example, 8 missing values in ‘‘driving experience’’ and 5 outliers in ‘‘questionnaireduration’’). In these cases, differences between groups of participants with missing or apparently aberrant values and therest of the sample were analysed and, for each variable, t-test showed no statistically significant differences in ARDES-Spainscores between these groups. Thus, the following analyses were performed using the whole sample of 320 participants: (a)classical item analysis and reliability analysis of ARDES scores; (b) exploratory factor analysis to assess ARDES-Spain scoresdimensionality (extraction method: maximum likelihood; number of factor selection: parallel analysis); (b); (c) t-tests andanalysis of variance (ANOVA) to examine differences in ARDES scores due to gender and level of education; (c) Pearson cor-relation and partial correlation analysis between ARDES-Spain scores and age, and number of years driving; (d) t-test todetermine the association between ARDES and the presence of self-reported motor vehicle crashes and fines for trafficviolations.

J. Roca et al. / Transportation Research Part F 21 (2013) 43–51 49

3. Results

The descriptive statistics of each of the 19 items, along with the corrected item-total correlation values and the factorloading are shown in Table 3. The mean values range from 1.29 to 2.03. All items were averaged into a single score, withhigher scores representing greater attentional error propensity. ARDES scores had a mean of 1.55 (St. Dev. = .52), and the fre-quency distribution was positively skewed. The corrected item-total correlation values extend from .41 to .60. The lowestcorrected item-total correlation values corresponded to item 1 (‘‘Heading towards a known place, becoming distracted, andthen going several streets beyond it’’), while item 17 reaches the highest value (‘‘Realising that due to distraction, I haven’t evennoticed the traffic lights’’). The Cronbach’s alpha coefficient value was .88, indicating that the answerers are consistent acrossthe ARDES-Spain items. The factor analysis suggested a single factor that exceeded the parallel analysis criterion and ac-counted for 32.70% of the total variance. All 19 items had positive loadings on this factor, ranging from .41 to .72 (see Table 3).Taking together, the corrected item-total correlation, the Cronbach’s alpha coefficient values, and the factor structure, theARDES-Spain shows adequate psychometric properties similar to the original ARDES-Argentina reported by Ledesma et al.(2010).

To obtain validity evidence of the appropriateness of the ARDES to evaluate attentional error propensity of drivers inSpain, first, evidence on the relationships between ARDES-Spain scores and socio-demographic variables were analyzed.The result of the t-test did not allow rejecting the null hypothesis on the equality of the means when comparing men’sand women’s scores in the ARDES-Spain (t = 1.53; p = .27). In addition, the ANOVA did not show significant differences inARDES-Spain total scores due to the educational background of the participants (F = 1.92; p = .10). A statistically significantcorrelation was found between ARDES-Spain total scores and the age of the drivers (r = �.21; p < .001), suggesting that olderparticipants had a lower attentional error propensity. However, it should be noted that age is a variable strongly associatedwith driving experience (i.e., older participants are generally the drivers accumulating more years since passing the drivingtest; r = .90; p < .001). Thus, partial correlation between ARDES-Spain total scores and age controlling for the number of yearssince passing the driving test was obtained and the result was not significant (r = �.52; p = .36), suggesting that the reportednegative correlation between ARDES and age might as well be explained by differences in drivers’ experience.

To complete validity evidence of the predictive capacity of the ARDES-Spain, differences in ARDES total scores betweendrivers with and without traffic crashes were analyzed. The results of the t-test allowed to reject the null hypothesis on theequality of means and showed that drivers who reported traffic collisions with material damage (n = 46) were more prone toattentional errors while driving than drivers who did not report such events (n = 274) (t = 2.56; p < .05). Mean comparisonbetween drivers with and without crashes with injuries was not computed since only four participants reported such events.Traffic fines were not associated with ARDES-Spain scores.

4. Discussion

Recent research confirms the relevance of the proneness to make attentional errors while driving to explain road trafficaccidents. According to Spanish official reports (Dirección General de Tráfico., 2011), driver inattention was in 2010 a con-current factor in 39% of road traffic accidents, being this figure higher in highways (45%) than in urban areas (33%). Thesedata support the idea that driver inattention is, also in Spain, one of the main causes of road traffic crashes (see, for example,

Table 3Descriptive statistics and psychometric results of the 19 items in the ARDES-Spain. Mean, standard deviation (St. Dev.), factorloading and corrected item-total correlation are shown for each item of the scale.

Item Mean St. Dev. Factor loading Corrected item-total correlation

1 2.03 .88 .44 .412 1.40 .63 .48 .443 1.57 .71 .72 .564 1.68 .80 .50 .485 1.44 .71 .54 .476 1.65 .74 .67 .607 1.47 .73 .56 .538 1.82 .77 .56 .539 1.59 .71 .46 .45

10 1.56 .75 .45 .4411 1.39 .71 .56 .5412 1.60 .83 .49 .4713 1.58 .70 .60 .5414 1.41 .68 .51 .5015 1.44 .69 .48 .4916 1.42 .63 .41 .4217 1.45 .64 .66 .6018 1.29 .54 .56 .5419 1.63 .75 .53 .50

50 J. Roca et al. / Transportation Research Part F 21 (2013) 43–51

Klauer et al., 2006; Ranney, 2008; Stutts et al., 2001). Previous evidence (Ledesma et al., 2010) suggested that drivers differ intheir proneness to make attentional errors while driving, which may reflect a relatively stable pattern of behaviour associ-ated with attentional errors in different dimensions of everyday life and with particular psychological variables. Therefore,having culturally appropriated questionnaires is necessary to extend our knowledge of driver inattention phenomenon andits relationships to car crashes in Spain and in the different countries.

The main aim of this paper was to adapt and test the original Argentinean version of the Attention-Related Driving ErrorsScale (ARDES). Differences in culture, language, traffic regulations and driving habits existing between Argentina and Spainlead us to develop an adapted ARDES to the Spanish spoken in Spain and to Spanish driving and traffic context. Following ITCGuidelines (ITC, 2010), the ARDES-Spain was developed to improve the cross-cultural stability and applicability of the scale.The expert appraisal performed in the current study by five external independent experts meet the ITC Guidelines D1, whichrecommend researchers insure that adapted versions take full account of linguistic and cultural differences among the pop-ulations for whom the adapted instruments are intended (ITC, 2010). The expert suggestions on item contents and instruc-tions were accepted to increase the cultural appropriateness of the ARDES-Spain.

Psychometric results confirm that the ARDES-Spain has adequate psychometric properties to be a useful tool for evalu-ating the proneness to attentional errors in the Spanish driving population. Item-test correlations for ARDES-Spain items aresimilar to those of the original Argentinean version of the ARDES, while the Cronbach’s alpha coefficient value is a slightlyhigher for the ARDES-Spain (.86 and .89, respectively). The single factor solution reported by Ledesma et al. (2010) was alsofound for the ARDES-Spain, which can be considered a cross-cultural evidence of the equivalence level reached by bothARDES versions.The analysis of the relationships between ARDES-Spain scores and socio-demographic variables providesfurther validity evidence of the appropriateness of the adapted questionnaire. No statistically significant differences werefound in the proneness to driving attentional errors by sex or educational level, which is consistent with previous evidencewith ARDES-Argentina (Ledesma et al., 2010). A statistically significant correlation was found in the current study betweenARDES-Spain total score and the age of the drivers, suggesting that older participants had a lower attentional error propen-sity. Ledesma et al. (2010) failed to find an association between age and attentional errors using the ARDES-Argentina, whatthey attributed to an insufficient representation of the age group over 60 (about 3% of the sample). In the current study wehave observed a negative association between age and attentional errors using a sample with a higher representation of par-ticipants over 60 (5.6%). However, the valence of the observed correlation was not consistent with the expected effect of age(higher age, higher attentional errors) and indeed suggested a potential influence of a confounding variable, such as the accu-mulated experience (higher experience, less attentional errors). Actually, the statistically significant correlation between ageand attentional errors vanished when the effect of driving experience was partialled out, and thus the reported correlationbetween ARDES scores and age might as well be explained by differences in drivers’ experience. Future research will be use-ful to specifically address this possibility.

In addition, the ability of the ARDES-Spain to distinguish between drivers who reported traffic collisions and those whodid not was also examined. Consistent with Ledesma et al. (2010), results in the current study with the ARDES-Spain showthat drivers who reported traffic collisions with material damage were more prone to attentional errors while driving thandrivers who did not report such events (crashes with injuries were not compared due to insufficient instances). Besides,receiving traffic fines was not associated with ARDES-Spain scores, while Ledesma et al. (2010) found that participantsreporting traffic fines were more prone to driving attentional errors. This divergence between the two ARDES versions couldbe due either to differences in the sample composition (for example, a higher proportion of young drivers was used in Led-esma et al.’s study) or to the existing differences in traffic regulations and driving habits between Argentina and Spain (forexample, as described in Section 1.2, some studies suggest that cellular phone use might be higher in the latter country).

4.1. Limitations and future studies

Future studies with ARDES-Spain could also provide further evidence of the questionnaire validity to measure attentionalerror proneness by analysing its association with different cognitive and psychological variables. For example, Ledesma et al.(2010) found a theoretically consistent pattern of correlations between ARDES-Argentina scores and different questionnaireson cognitive and psychological constructs, such as attention and memory error proneness, lack of general awareness andattention, proneness to boredom, and also dissociative personality traits. Besides, recent evidence with the ARDES-Argentina(López-Ramón et al., 2011) and with the DBQ (Roca, Lupiáñez, López-Ramón, & Castro, 2013) associated the proneness toattentional errors while driving with drivers’ attentional performance using computer-based neurocognitive tests (such asthe Attention Networks Test by Fan et al., 2002; and the Attention Networks Test for Interactions and Vigilance by Rocaet al., 2011). Similar results would be observed with the ARDES-Spain to provide further evidence of the questionnaire.

Regarding the cross-cultural equivalence of the ARDES, the current study provides evidence to claim a similar functioningof both the Argentinean and the Spanish versions of the questionnaire. However, it is possible that significant differences willarise when adapting the ARDES to other cultures. Thus, further evidence to discuss the cross-cultural equivalence of thequestionnaire would be obtained when carrying out new adaptations to other countries with different languages, cultures,traffic regulations and driving habits. For example, ongoing research efforts are currently being made to obtain a version ofthe ARDES adapted to British English and to the culture, the Highway Code and the driving habits in the United Kingdom.

J. Roca et al. / Transportation Research Part F 21 (2013) 43–51 51

Acknowledgments

This research was partially funded by the Ministerio de Ciencia e Innovación in Spain (PSI2010-15883 and SEJ-2007-61843), the Junta de Andalucía (PO7-SEJ-02613, P10-SEJ-6569 and P11-SEJ-7404), and the Fondo para la Investigación Cientí-fica y Tecnológica in Argentina (PICT-2008-1502). None of the funding sources had a direct involvement in the study design,in data collection, analysis or interpretation, in the writing of the report or in the decision to submit the paper for publica-tion. Also, we would like to thank the Dirección General de Tráfico (DGT) and the Fundación para la Seguridad Vial (FESVIAL) forsupporting the present research as observing promoters (Entes Promotores Observadores).

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