the closed circle of empathy: mirror neuron system …...ii the closed circle of empathy: mirror...
TRANSCRIPT
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The closed circle of empathy: mirror neuron system activation and anterior EEG
asymmetries in response to outgroup members.
by
Jennifer N. Gutsell
Master’s thesis submitted in conformity with the requirements
for the Masters of Arts and Science
Department of Psychology,
University of Toronto, 2009
© Copyright by Jennifer Nadine Gutsell (2009)
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The closed circle of empathy: mirror neuron system activation and anterior EEG asymmetries
in response to outgroup members. - Jennifer N. Gutsell, Department of Psychology,
University of Toronto, 2009
Abstract
Empathy varies with similarity and familiarity of the other. Since outgroups are seen as
dissimilar to the self, empathy might be restricted to the ingroup. We looked at two neural
correlates of empathy: mirror neuron system activation as indicated by
electroencephalographic mu suppression and prefrontal alpha asymmetry. Non black
participants watched videos of ingroup and outgroup members acting and expressing
emotions, and then acted and experienced emotions themselves. Due to methodological
problems, mirror neuron system activation was not obtained. However, anterior asymmetries
indicated avoidance motivation during the experience of sadness and the mere observation of
sad ingroup members while participants did not show anterior asymmetry when observing the
black outgroup. These findings suggest that empathy is bounded to a closed circle of similar
others.
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Table of Contents
Abstract… ..........................................................................................................ii
Table of contents… .......................................................................................... .iii
List of Tables… ................................................................................................ .iv
List of figures… ................................................................................................. .v
Introduction….. .................................................................................................. 1
Theoretical Background .................................................................................... 2
Empathy – a definition… ..................................................................................... 2
How do we empathize? – The Perception Action Model of empathy .................... 4
The stages of empathy .......................................................................................... 5
The limits of empathy – moderators for empathic responses ................................. 8
The mirror neuron system – a neural account for vicarious emotions and the
basis of empathy – moderators for empathic responses ...................................... 10
Prejudice and the distinction between “us” and “them” ....................................... 14
Perceiving others as different ............................................................................. 15
Social neuroscientific methods to measure empathy ........................................... 16
Measuring Mirror Neuron System activation ........................................... .16
Measuring vicarious prefrontal alpha asymmetries .................................... 18
Overview ........................................................................................................... 20
Method .............................................................................................................. 21
Participants ........................................................................................................ 21
Procedure ........................................................................................................... 21
Stimulus Materials ............................................................................................. 22
Measures ............................................................................................................ 24
Measures of ingroup favouritism .............................................................. 24
Measures of empathy ................................................................................ 25
EEG data acquisition and processing .................................................................. 35
Results ............................................................................................................... 26
Mu suppression .................................................................................................. 26
Anterior Alpha Asymmetry ................................................................................ 27
Behavioural measures ......................................................................................... 30
Correlation with empathy………………………………………………….30
Correlation with ingroup favouritism – IAT, MRS and IOS……………...31
Discussion ......................................................................................................... 31
Limitations and further directions ....................................................................... 34
Conclusions ........................................................................................................ 35
References ......................................................................................................... 37
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List of Tables
Table 1 Correlations between anterior alpha asymmetry scores and the measures
of ingroup favouritism and empathy………………………………………….…5
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List of Figures
Figure 1 The human MNS and its main visual input in action understanding and
imitation...….. ..................................................................................................... 5
Figure 2 Anterior alpha asymmetry scores during the two emotion conditions
(Sad, Happy) for ingroup, self and black. ............................................................. 5
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I am a Jew. Hath not a Jew eyes? Hath not a Jew hands, organs, dimensions, senses,
affections?
--From The Merchant of Venice (III, i, 60-63)
In the quote above, the character of Shylock pleads for empathy and equal treatment
noting that Jews bleed when pricked, laugh when tickled, and killed when poisoned. Given
our shared humanity, then, why does prejudice seem so inevitable? To answer this question,
the current study looks at the basic processes involved in prejudice by taking a closer look at
brain activity. I propose that the neural systems involved in empathy and action understanding
are less responsive to outgroup members than ingroup members, leading people to ignore the
shared humanity of others.
Empathy is the capacity to recognize and understand other people’s experiences, needs,
and goals, and thus facilitates social understanding and cooperation. Empathy is bounded,
however: it varies as a function of similarity and familiarity of other people (Preston & de
Waal, 2002). According to self-categorization theory (Turner, 1987), ingroup favouritism and
prejudice result from the intersection between one’s self and one’s ingroup. Once one
identifies with a group, the self and the group merge to become interchangeable. The self,
importantly, overlaps with the ingroup, but not with the outgroup. This overlap facilitates
perspective taking and empathic reactions. On the other hand we might be less sensitive to the
feelings of outgroup members and less likely to take their perspective. If people do not feel
other people’s pain, the door for discrimination is wide open. The aim of the current study is,
first, to investigate whether empathy is bounded to ingroup members and, thus, excludes
outgroup member and, second, to find a neural account for why empathy is bounded. To
achieve these goals, this study draws on neuroscientific research on empathy and perspective
taking.
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In what follows, I will first review research on empathy and which factors promote and
prevent empathy. Second, I will present a neuroscientific view on empathy and discuss its
potential origins in our evolutionary history. Third I will discuss prejudice and its causes. I
will further describe the concept of self-other overlap and dehumanization of outgroups, and
connect them to prejudice. I propose that the perceived distance between groups impairs
empathy towards these groups and that this is reflected in the neural processes underlying
empathy. I will, then, discuss two neural correlates and potential measures of empathy –
mirror neuron system activity measured by EEG mu rhythm suppression and asymmetries in
the activity of the prefrontal cortex measured by anterior alpha asymmetries. Third, based on
this theoretical background, I will develop an appropriate research method for examining the
role of the mirror neuron system in prejudice. I will then describe the research design and the
empirical and analytical methods. Finally I will present the results and discuss their
implications.
Theoretical Background
Empathy - a definition
Empathy is generally referred to as the ability to feel with others (Batson et al., 1997).
Usually, when we see others in pain, we suffer along with them and this is one of the building
blocks of human and animal societies (McDougall, 1923). In addition to this fundamental
function, empathy is the basis for numerous important social processes (Carr, Iacoboni,
Dubeau, Mazziotta & Lenzi, 2003). First, empathy functions as the driving force behind
helping behavior (Dovidio, Allen, & Schroeder, 1990; Batson et al., 1997) and other prosocial
behavior, such as cooperation, moral sense, altruism, and justice (Vignemont, & Singer,
2006). Second, in addition to its effects on prosocial behavior, empathy promotes
understanding and, therefore, influences people’s attitudes towards others (Batson et al.,
1997). Feeling empathy for someone elicits a concern about the welfare of the other person.
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This increase in concern persists even after empathy lessens (Batson, Turk, Shaw & Klein,
1995). Third, empathy helps one to predict others’ future behaviour and to understand their
motivational states and goals (Vignemont, et al., 2006). Therefore, empathy is a very effective
tool for social understanding and leads to smooth social interactions. Finally, empathy
facilitates social communication. When we empathize with others, we tend to imitate or
mirror their intonations, gestures, and postures. This imitation elicits fondness and affiliation
in others (Lakin & Chartrand 2003). Similarly, perceiving that others empathize with us
improves our opinion about them (Chartrand, Bargh, 1999).
Because of its importance people have researched empathy for many years (Batson,
Fultz, & Schoenrade, 1987, Cialdini, Brown, Lewis, Luce, & Neuberg, 1997, Hume 1888,
Lipps, 1903 (as cited in Preston, & de Waal, 2002). Despite this interest, researchers still
disagree about what constitutes empathy (Preston, & de Waal, 2002). Some define empathy as
an affective response more appropriate to another’s situation than one’s own (Hoffman,
2000), affect sharing (Preston, & de Waal, 2002), or the sensitivity to and understanding of
the mental states of others (Smith, 2006).
These relatively broad definitions subsume a whole array of related sub concepts that
can be separated into two categories: emotional empathy and cognitive empathy. Emotional
empathy highlights the aspect of feeling others emotions. It includes more basic processes
such as emotional contagion or personal distress (e.g. I feel sad because I see that you feel
sad) and higher order processes that go beyond the mere mirroring of others’ emotions. For
example, empathic concern (Batson, Fultz, & Schoenrade ,1987) results from further
processing based on the information obtained from vicarious emotions (e.g. I feel sorry for
you because you are sad). Cognitive empathy, on the other hand, is the understanding of the
other’s emotional state as opposed to simply vicariously feeling with the other. It includes
phenomena such as cognitive perspective taking (e.g. because I know you and your situation I
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infer that you are sad) and theory of mind. Sometimes a more restrictive definition of empathy
is necessary to allow precise hypotheses and predictions for research purposes (Batson et al.,
1987, Vignemont, & Singer (2006). However, following Preston and de Waal’s (2002)
approach, I see empathy as a concept that joins all phenomena that are based on the same
underling process – the vicarious experience of the emotions of another person. Such a
process based concept of empathy defines empathy in even broader terms than the definitions
discussed above. It includes all levels of empathy related phenomena starting from emotional
contagion to sympathy, guilt, cognitive empathy, and finally even helping behaviour. It also
links empathy to related behaviours such as imitation and priming. Hence, using a process
based definition of empathy enables us to look at the whole array of behaviours that constitute
much of our social nature and, at the same time, to focus on their joint evolutionary origins
and neural basis (Preston, & de Waal, 2002).
How do we empathize? The Perception Action Model of empathy
According to Preston and de Waal (2000) empathy is based on the same mechanism as
motor behaviour – the perception-action mechanism. Actions and the mere perception or
imagination of the same actions share common representations (Prinz, 1987). Through these
common representations, observing behaviour automatically activates and facilitates the same
behaviour in the observer. For example, hyenas are 70% more likely to drink when they see
co specifics drinking (Glickman et al. 1997). Further, Muesseler and Hommel (1997) found
that participants were unable to perceive a stimulus that represented a certain action (e.g. right
key press) while they performed that same action (e.g. pressing the right key), even though
they could easily perceive the stimulus when it did not correspond with the action (e.g. while
pressing the left key). These findings show that, because perception and action share the same
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representation perception and thus are incompatible with each other, perception is blocked
when the representation is used for acting (Chartrand, & Bargh, 1999).
Linking perception, imagination and action through a common representation is
evolutionary highly adaptive since it enables the organism to react quickly and appropriate to
its environment (Preston, & de Waal, 2002). Social animals and especially primates, who rely
heavily on their co specifics for survival, use the action perception link to navigate through
their complicated social systems (Preston, & de Waal, 2002). When someone (the subject)
observes another (the object), the subject has access to the object’s inner states, because the
mere observation activates the same neural and bodily representations in the subject. Through
this mechanism the subject feels with the object; it happens without intention or
consciousness, and that is what we call emotional contagion. Chartrand and Bargh (1999)
proposed that the action perception link consists of three steps. First, the subject observes the
targets facial expression and bodily postures, in a second step this observation activates the
subjects own representations. Finally, this activation increased the tendency for the subject to
behave in the same way as the object. As proposed in the facial feedback hypothesis (Izard,
1990, James, 1913, Laird, 1974), once the subject has adopted the object’s expressions and
posture, these elicit bottom-up processes that elicit the correspondent emotions. Therefore, by
enacting the object’s emotions, the subject experiences these emotions – the ground for
empathy is laid. This emotional contagion is the most basic process in empathy and seems to
be biologically hard wired (Atkinson, 2002). However, as soon as higher order cognitive
processes become involved more sophisticated forms of empathy evolve.
The stages of empathy
Empathy consists of three different stages: Emotional contagion, empathic concern and
empathic perspective taking (de Waal, 2008). Emotional contagion of negative emotions
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results in personal distress. This stage is not altruistic. Instead, it is self focused; since the
negative feelings, elicited by the other, cannot be distinguished from one’s own feelings. The
observer feels distressed but does not, or cannot, take the next step of distancing him- or
herself from these feelings. This self centered empathy leads to the selfish motivation to
alleviate one’s own pain. One can ease one’s pain by either reducing the distress of the other
through helping, or by leaving the distressing situation and turning one’s back to the sufferer
(Batson, Fultz, Schoenrade, 1987). This negative side of personal distress was shown by rats
who failed to press a button to save another rat that suffered from electric shock. Instead of
helping the other rat, they crunched fearfully in the furthest corner expressing high levels of
distress (Rice, 1962). For many species, emotional contagion is the only form of empathy and
it often proves to be useful, for instance, when a flock of birds flies away from a predator after
hearing the distress signals of a flock member, or when a rat mother comes to help one of its
pups squeaking in distress.
The next evolutionary step of empathy and the next step in child development is
empathic concern. Here, while the subject feels the emotions of the object, the process does
not stop. Instead, the subject is aware that the object is the source of its emotions and can
appreciate and comprehend the other’s situation (De Waal, 2008). This new distinction
between internally and externally generated emotions opens the door for more sophisticated
empathic emotions – emotions such as guilt, compassion, sorrow, but also spitefulness,
resentment and envy. Often, empathic concern evokes an other-oriented, altruistic motivation
to alleviate the other’s distress (Batson 1991).
However, at this stage, “real empathy”, or what the lay person would consider to be
empathy, is not yet achieved. We generally speak of empathy only when it involves
perspective-talking. Only when we feel with the other and consequently feel for the other, and
we understand the other and his situation, we say that someone truly empathizes with another
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(de Waal, 2008). Hence, top down processes are involved in empathy. The subject takes the
object’s perspective and imagines their mental state and situation to understand the emotions
the subject sensed from the object through emotional contagion. Thus, the third and last stage
of empathy is empathic perspective taking – the cognitive process of taking the other’s
perspective plus empathic concern. Empathic perspective taking can result in targeted
helping, which is helping adapted to the specific needs and goals of the other (de Waal, 2008).
This happens, for instance, when a mother hears her baby crying. Initially feeling distressed
herself; she quickly shifts perspectives and consequently feels compassion with the baby and
a strong motivation to alleviate the baby’s distress. She, then, assesses the baby’s situation,
taking into account what she knows about its preferences, goals, and behavioral patterns, to
infer what caused the distress and what can reduce it. She might then come to the conclusion
that the baby is hungry and will take steps to feed the baby. Without the initial vicarious
distress, however, the mother would lack the basis for all subsequent steps in her progress to
helping. Because she would not feel with the baby, she would see her babies’ distress signals,
but would not understand what they mean. Although she could try to infer what they mean by
top down processing, for example recollecting what she knows about babies and that their
crying indicates that they are in need of something. Nonetheless, she would still lack the
emotions necessary to fuel the motivation to help. Research on anti-social personality disorder
illustrates this point. Individuals diagnosed with this disorder are said to lack the ability to feel
with others. They are able to severely harm and sometimes kill others because they are
unresponsive to other’s distress signals (Blair, 1997). Despite their lack in empathic concern,
individuals with anti-social personality disorder have intact cognitive functions and are fully
capable of cognitive perspective taking (Blair, 2008). Thus, without the ability to feel with
and for others, all cognitive reasoning is useless. The experience of vicarious emotions is vital
for all subsequent stages of empathy. Recent findings, however, suggest, that this basic and
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automatic process is not as universal as one would expect. Empathy was shown to be biased
and restricted by certain factors and this might even start at its crucial basic process.
The limits of empathy – moderators for empathic responses.
Whether we empathize with someone or not depends on perceived similarity (Cialdini,
Brown, Lewis, Luce, & Neuberg, 1997), familiarity with the target (Cialdini, et al. 1997),
need for nurturance and protection of the target (Batson, et al., 2005), and affiliation with the
target (Vignemont & Singer, 2006). For example, in an experiment on the effects of similarity
on empathy, participants where led to believe that an ostensible second participant was similar
or dissimilar to them. They, then, saw the other participant getting electric shocks.
Participants showed heightened arousal and reported more empathic emotions when the other
was similar as compared to when he was different. Apes, also, empathize more with familiar
apes who received electric shocks then with unfamiliar apes (Miller, Murphy, & Mirky,
1959). Moreover, Cialini, et al. (1997) found that in humans, emphatic concern for others is
eliminated when one controls for “oneness” – the degree to which participants perceive
themselves in the other.
The reasons why similarity, familiarity and affiliation promote empathy lay in our
evolutionary history. According to the concept of inclusive fitness (Hamilton, 1964, as cited
in Cialdini, et al., 1997), individuals do not act to secure their own welfare but to secure the
welfare of their genes. Hence, from an evolutionary perspective, it is irrelevant whether one
survives or two of one’s siblings survive. In both cases, the contribution of one’s own genes
to the gene pool is the same. From the perspective of evolution, then, empathy and prosocial
behaviour should be determined by their contribution to reproductive success in ancestral
environments. Hence, one can preserve one’s genes by promoting the survival of those who
share one’s genetic make-up. Since people can promote their own evolutionary success by
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helping relatives (Sime, 1983), inclusive fitness can explain altruistic behaviour within
families. When a mother saves her children by risking her own death, according to inclusive
fitness, this is a smart thing to do. Following this strategy it is easy to determine who to help
and who not to help when dealing with relatives. When asked how they would respond to
various situations in which someone needed help, participants expressed more motivation to
help close relatives and especially younger and healthy ones (Burnstein, Crandall, &
Kitayama, 1994).
Relatives are not the only ones with whom we share genes. Our genetic makeup
overlaps with other people as well; sometimes even with strangers. At one point in our
evolutionary history we had a common ancestor with everyone. What counts is the degree of
genetic overlap we share with others. Since this degree of genetic overlap is impossible to
detect, we must rely on cues that usually come along with genetic similarity. The more similar
someone is to us, the more likely it is, that he or she shares at least some of our genes.
Therefore, similarity is an important factor leading to empathy and prosocial behaviour
(Krebs, 1991). Natural selection not only operates on individuals, it can operate on groups as
a whole. Humans can sometimes increase their reproductive success by protecting their
groups’ interests as opposed to the interests of other groups (Wilson & Sober 1998). This
could explain, at least in some part, why we empathize with and help others who are unrelated
but socially connected to us.
Knowing that similarity influences empathy, an important question is at which stage of
empathy does similarity moderate the empathic reaction? Most behavioural studies cannot
provide an answer to these questions since they investigate the result of the process through
empathic behaviour or self report and these approaches are insufficient to distinguish between
the different stages of empathy. However, research on the neural basis of empathy suggests
that the most basic processes in empathy are sensitive to similarity, familiarity and affiliation
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of the object. This research examines the mirror neuron system - a neural system said to be
the basis for the perception-action link and which can provide useful insight in the basic
mechanisms underlying empathy.
The mirror neuron system – a neural account for vicarious emotions and the basis of empathy
The idea of the perception-action mechanism had been around for several years before it
gained additional support from the neurosciences. While recording single cell activity in the
monkey premotor cortex, an area usually responsible to retrieve the appropriate motor act in
response to sensory stimuli, Rizzolatti, Fadiga, Fogassi, and Gallese (1996) discovered that
premotor neurons fire when the monkeys grasped food and when the monkeys simply
observed the experimenter doing so. Since, during observation, these cells “mirror” the
activation patterns that produce that same action, they have been called “mirror neurons”.
Further research on mirror neurons revealed that they only respond to biological, object-
directed actions (Rizzolatti, & Luppino, 2001). For example, mirror neurons are unresponsive
to the mere sight of an object and actions without an object being present. Further, an action
performed by a mechanical device is not effective either .These specific demands for the
subject, action and object suggests that mirror neurons represent goal-directed actions
(Rizzolatti & Arbib, 1998). These representations enable individuals to understand and imitate
others’ actions and goals (Rizzolatti, Craighero, 2004). After the discovery of the mirror
neuron system in monkeys, the research focus shifted to humans. Behavioural,
neuropsychological, and imaging studies with positron emission tomography (PET),
functional magnetic resonance imaging (fMRI) and electroencephalography (EEG)
established that humans, indeed, have a mirror neuron system (Buccino, Ferdinand, & Lucia,
2004; Rizzolatti, & Craighero, 2004). In humans the observation of actions activates a
complex network formed by occipital, temporal, and parietal visual areas. The core of the
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human mirror neuron system is the rostral part of the inferior parietal lobe and the lower part
of the precentral gyrus plus the posterior part of the inferior frontal gyrus (IFG) - brain
regions primarily specialized in motor functions, action planning and intentions (Rizzolatti &
Craighero, 2004) (Please see figure 1 for a depiction of the human mirror neuron system).
Similar to the monkey’s mirror neuron system, the human mirror neuron system reacts to the
sight of biological movements, the abstract and general representations of actions, and it is
especially receptive to intentional action (Rizzolatti, Fogassi, Gallese, 2001). With these
properties, the mirror neuron system seems to serve a mapping function (Fogassi et al., 2005).
Rizzolatti et al. (2001) propose that the mirror neuron system is the basis for the perception
action mechanism; we understand actions when we map the visual representation of the
observed action onto our motor representation of the same action.
Figure 1: The human MNS (in red) and its main visual input (yellow) in action understanding
and imitation. The MNS in the rostral inferior parietal lobule (IPL) is primarily concerned
with the motoric description of the action. The frontal MNS located in the Prefrontal Motor
Cortex (PMC) and Inferior frontal Gyrus (IFG) is more concerned with the goal of the action.
The yellow and red arrows represent the flow of information from visual to motor and
Iacoboni and Dapretto (2006)
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prefrontal areas. The black arrows represent an efferent copy send back from prefrontal
cortex to posterior Superior temporal sulcus (STS).
If we want to apply the perception action mechanism to emotions and empathy, things
become more complicated. The brain areas underlying the mirror neuron system are generally
not involved in emotions (Iacoboni & Lenzi, 2002). Then, how can the mirror neuron system
be the basis of empathy? The insula connects limbic areas, which generate emotions, with the
areas involved in the mirror neuron system and, as shown by fMRI studies, the insula is
heavily involved in affect generation during imitation tasks. Hence, the insula is the necessary
link between the action oriented mirror neuron system and emotional areas, providing a
possible pathway from observation of motor behaviour, such as expressions and body posture,
to empathy (Carr, et al., 2000, Iacoboni, Lenzi, 2002).
Several brain imaging studies further support the action-perception model of empathy. 2
In all of these studies, mirror neuron system activation appeared almost automatically;
whenever participants observed emotions, the mirror neuron system was active. But, are
mirror neurons really automatically triggered every single time we see someone’s emotions?
As we have seen, empathy is more selective. Is this true even at this most basic level of
empathy?
Recent studies suggest that some kind of moderation processes determine activation of
the mirror neuron system. In their research on mirror neuron system function, Oberman,
Pineda, & Ramachandran (2006) showed participants videos that differed in the degree of
social interaction. In the “no interaction”condition, participants saw three individuals standing
in a circle, each of them tossing a ball in the air and catching it. In the “medium interaction”
condition the three individuals tossed the ball to each other and in the “high interaction”
condition the three individuals tossed the ball to each other, but sometimes they tossed it off
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the screen, seemingly to the observer. Thus in the no interaction condition there was no
interaction between the three individuals nor was there any interaction with the observer. In
the medium interaction condition, the three individual interacted but they did not interact with
the observer. Finally, in the high interaction condition, the three individual interacted and they
also interacted with the observer. As measured with the EEG, mirror neuron system activation
was moderated by the degree of interaction. When the participants were included in the
interaction, their mirror neurons fired the most, followed by interaction without involvement
of the participant, and the least activation in the no interaction condition. Hence, mirror
neuron activation depends on the degree of social interaction and mirror neurons are
especially active when there is face-to-face interaction. These results show that the mirror
neuron system is reactive to variations in social content. Singer, et al. (2006) provided further
support for the mirror neuron system’s sensitivity for social content. They found evidence that
mirror neuron system activation is moderated by the affective link between individuals. To
manipulate liking versus disliking, they let their participants play an economic game with two
ostensible other participants, who were actually confederates. One of the two confederates
played unfair and the other played fair. Later, mirror neuron system activation was measured
with f MRI while participants watched the confederates receive seemingly painful stimuli
administered to their hands. Both, male and female participants exhibited mirror neuron
system activation in pain-related brain areas when they saw fair players feeling pain. Male
participants showed significantly reduced mirror neuron system activation towards the unfair
players, whereas female participants showed mirror neuron activity in response to both
players. At the same time only males showed increased activation in reward-related brain
areas and they later expressed the desire for revenge.
Taken together, research on the neural processes involved in empathy confirms the
perception action model of empathy– we know what others feel because we actually feel it,
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and we feel their emotions because we simulate them in our brains. Even these basic
mechanisms seem to be influenced by similarity, familiarity and affiliation, thus bounding
empathy to certain others. This bias towards similar, familiar and affiliated others suggests
that there is a fundamental difference in how our brain processes information about people to
whom we have different social relations and attitudes. This might have far reaching
consequences for interactions with individuals who cannot activate our mirror neuron system.
We might not be as responsive to these people’s needs, and less likely to understand their
intentions; we might be less likely to help them, and might communicate less effectively with
them. Usually our ingroup members are the ones who are similar to us, who we are familiar
and affiliated with. So what about outgroups? Is it possible that we empathize less with
outgroup members? Research on prejudice suggests that this might be the case.
Prejudice and the distinction between “us” and “them”
Prejudice can be defined as an unfair negative attitude toward a social group or a
member of that group (Dovidio, & Gaertner, 1999). People prefer their ingroup to an outgroup
(Perdue, Dovidio, Gurtman, & Tyler, 1990), they assign more positive attributes to the
ingroup than to the outgroup (Gaertner Mann, Murrell, & Dovidio, 1989), and they show less
helping behaviour towards outgroup members (Dovidio, et al., 1997, Frey, & Gaertner, 1986).
Interestingly, empathy seems to be an antidote for prejudice (Batson et al., 1997; Galinsky, &
Moskowitz, 2000). The determining factor for these biases might be similarity.
In social identity theory, Turner, Brown, and Tajfel (1979) introduced the concept of
self-categorization. People who identify with a group come to perceive themselves not as
unique personalities with individual differences, but as interchangeable parts of a group. As a
result, the self and the group merge and the group identity becomes an integral part of the self.
When people merge with their group, they tend to stress similarities with the ingroup and
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differences with the outgroup. Thus the self and the ingroup become seemingly more similar,
whereas the gap between the self and the outgroup grows. Consequently, people perceive
outgroup members as radically different from their own group. This distinction can even lead
to the feeling that others lack typically human characteristics (Leyens, et al., 2000). As a
result, people sometimes consider outgroup members as less than human.
Perceiving others as different
Fiske, Cuddy, Glick and Zu (2002) addressed the question, why we sometimes ignore
the shared humanity of outgroup members, in their stereotype content model. According to
this model the extent to which we deny others their full humanity depends on their group
membership. We judge groups on two dimensions: warmth - the group intends to help and not
harm us - and competence - the group is capable of enacting those intentions. Groups who are
high in warmth and competence elicit respect and admiration. Mostly this is the case for one’s
ingroup. However, when we judge a certain group as low in warmth and low in competence,
the elicited emotions are disgust, disrespect, and dislike (Fiske, Cuddy, Glick, & Zu, 2002).
Such devalued groups are most likely to be seen as less than human and are often
dehumanized (Harris & Fiske, 2006). Dehumanization is the most extreme form of prejudice
and it applies for example to homeless people, drug addicts and sometimes, but to a lesser
degree, ethnic groups and in particular Arabs and Blacks.
Not all outgroups are dehumanized, and those who are, are not necessarily dehumanized
to the same extent by everybody at all times. Sometimes people devalue others only in certain
domains. For example, people judge outgroups as inferior especially in typically human
characteristics such as intelligence (Crocker, Major, & Steele, 1998), and social competence
(Glick & Fiske, 2003). Interestingly, Leyens and colleagues (2000) found that people deny
outgroup members of having certain, characteristically human emotions. These so-called
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second order emotions, for example jealousy and contempt, differ from primary emotions
such as anger and curiosity in that they are more complex, internally caused, more invisible,
and more cognitive. They occur only later in age, are less intense, and more persistent.
Secondary emotions are not ascribed to animals (Leyens et al., 2000). For example, dogs can
be frightened, angry, or even surprised, but one would not say that a dog admires something
or feels disillusioned. The restriction of secondary emotions to be exclusive for ingroups
enlarges the gap between different groups and further fosters a sense of dissimilarity between
groups. If people do not feel related and affiliated with outgroup members and perceive them
as dissimilar, they might have a harder time to empathize with them. To investigate whether
we feel less empathy toward outgroup members and to specify what particular aspect of
empathy might be impaired, we attempt to look beyond the behavioural level of empathy and
to investigate by using the social neuroscientific approach.
Social neuroscientific methods to measure empathy
A recurrent problem in research on intergroup bias is how to measure it. People often
are unwilling to reveal their prejudice and often are not even aware of them (Guglielmi,
1999). Thus research participants might not be willing or able to report possible bias in
empathy towards outgroups. Moreover, conventional measures of empathy, such as self report
and helping behaviour, do not allow to distinguish between the different levels of empathy (de
Waal, 2008), which leaves researchers unable to make inferences about the specific
mechanisms that lead to a lack in empathy. To avoid these problems, the current study uses
the EEG to measure mirror neuron system activity, and to measure vicarious emotions
through prefrontal alpha asymmetries.
Measuring Mirror Neuron System activation.
Mirror neuron system activation has been measured using several methods, including
transcortical magnetic stimulation (TMS), fMRI and EEG. Because the EEG is a non-
17
invasive, inexpensive method to measure mirror neuron activity online, we chose EEG as the
main dependent measure of this study.
The EEG measures mirror neuron activity by comparing electrical signals from
sensorimotor neurons at rest and during the experimental conditions. At rest sensorimotor
neurons spontaneously fire in synchrony, leading to large amplitude EEG oscillations in the 8-
13HZ frequency band called mu band. When participants perform an action, these neurons
fire asynchronously, and therefore, the power of the mu oscillations weakens. The connection
between mu rhythms and mirror neuron activity was first suggested by Altschulter et al
(1997). According to Altschulter the mu rhythm reflects the downstream modulation of
sensorimotor neurons by cells in the premotor cortex, some of which are mirror neurons.
However, when people observe actions or emotions in others, then mu rhythm reflects mirror
neuron activity exclusively (Pineda, 2005). The relationship between mu rhythm and mirror
neuron activity is supported by several similarities in properties between the mu rhythm and
mirror neurons. First the mu rhythm is generated by activity in mirror neuron areas. Second
mu rhythm is suppressed during action, but also during the observation of action (Cochin,
Barthelemy, Lejeune, Roux, Martineau, 1998). Third, the mu rhythm reacts more strongly to
goal directed actions than to non goal directed actions, and when the action is object oriented
compared to non object oriented (Muthukumaraswamy, Johnson, McNair, 2004). Because of
this overlap in location and functional properties, researchers agree that mu suppression can
be used as a selective measure of mirror neuron system activity (Oberman, et al. 2006). As
discussed above, mirror neurons are said to be the very basis of emotional contagion (Gallese,
Ferrari, & Umilta, 2002), but the absence of mirror neuron activity does not necessarily equal
the absence of empathy. Similarity and familiarity could exert their influences to a higher
more cognitive level of empathy. Thus, we need a direct measure of the vicarious emotions
constituting empathy.
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Measuring vicarious prefrontal alpha asymmetries.
A potential measure of vicarious emotions is anterior frontal asymmetries as measured
by relative EEG alpha wave strength in the right vs. left prefrontal cortex. Although a
relatively broad measure of general motivation, it can distinguish between positive, approach
related, emotions (e.g. happiness) and negative, avoidance related emotions (e.g. sadness)
(Harmon-Jones, & Allen, 1998). The earliest finding on asymmetrical organization of the
prefrontal cortex comes from research on patients with brain damage to one hemisphere. For
example, patients showed symptoms of depression after damage to the left hemisphere of the
prefrontal cortex and mania after damage to the right hemisphere (Robinson, Kubos, Rao, &
Price, 1984). These discoveries fed an extended research line on EEG alpha asymmetries in
the prefrontal cortex (Fox et al., 2001, Harmon-Jones, & Allen, 1998, Jones, Field, &
Davalos, 2000, Sutton & Davidson, 1997). This research consistently showed that the left
prefrontal and the left anterior temporal cortex are involved in the experience and expression
of positive, approach related emotions and that the right prefrontal and the right anterior
temporal cortex is involved in the experience and expression of negative, avoidance related
emotions (Davidson, Ekman, Saron, Senulis, & Friesen, 1990). This functional asymmetry is
measured by comparing of EEG alpha band activity of both hemispheres either at rest or
during different experimental conditions. This method revealed, for example, that
asymmetries in alpha in the prefrontal cortex are associated with depression (Allen, Iacono,
Depue, & Arbisi, 1993), a general trait like emotional style (Wheeler, Davidson, & Tomarken,
1993) and with emotional responses elicited by negative vs. positive films (Davidson, et al.,
1990).
When we speak about findings gained from frontal alpha asymmetries we are mainly
talking about activity in the dorsolateral prefrontal cortex (Davidson, 2004). That is because
19
the dorsolateral prefrontal cortex is the brain structure most likely to be directly reflected in
the EEG (Davidson, 2004). The dorsolateral prefrontal cortex is involved in cognitive control,
and has strong connections with the orbital prefrontal cortex, a structure that assigns affective
value to stimuli. Thus, the dorsolateral prefrontal cortex is essential for processing of reward
and punishment. Along this line, neurophysiological research on primates suggests that
reward and punishment information is passed from orbitofrontal to dorsolateral prefrontal
cortex which then uses this information to guide behaviour (Wallis and Miller, 2003). Hence,
although it seems that positive and negative emotions are lateralized within the prefrontal
cortex, it really is the motivational component of these emotions. To distinguish the
motivational aspect from the valence of emotions, Harmon-Jones and Allen, (1998) looked at
anger, an emotion that has a negative valance but an approach motivational value. The
negative valance should lead to left-frontal activity, whereas the approach component should
lead to right-frontal activity. The researchers found that anger was associated with right-
anterior activity and, thus, the left dorsolateral cortex. Hence, emotions guide our behaviour
by means of approach and withdrawal motivation, motivating us to either move towards or
away from stimuli. Usually, positive emotions are associated with approach motivation, for
instance love leading us towards another person, while negative emotions are associated with
avoidance motivation, for instance fears driving us away from another person. This
motivational aspect of the experienced emotions is what we can investigate with frontal EEG
asymmetries. Hence, anterior alpha asymmetries, when measured in a social setting, provide
us with a measure of vicarious emotions. Moreover, since the prefrontal cortex seems to be
exclusively involved in the experience and expression of emotions and not the perception of
emotions (Davidson, 1994), Alpha asymmetries are a measure of vicarious emotions free of
any confounds from the mere perceptions of emotions.
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We used anterior alpha asymmetries as a measure for vicarious emotions, and to
investigate the neural process underlying these vicarious emotions, we used EEG mu rhythm
as an indicator of mirror neuron activity. We asked whether people process actions and
emotional reactions of ingroup members differently than those of outgroup members. Taking
together, evolutionary humans are equipped with an empathy system that allows them to
navigate their social system, by understanding the emotional and cognitive states of others.
However, this system evolved in a way that that makes us empathize more with similar
people. Similarity and familiarity seem to even influence our most basic emphatic processes –
the ability to feel with others by simply simulating their emotions. In this context research
findings on Prejudice, categorization and dehumanization are alarming: If we feel less similar
to outgroups than to ingroups, sometimes to the degree that we see them as less human, do we
even distinguish between them on a neural level? Is our mirror neuron system less sensitive to
outgroup members and is empathy bounded to our ingroup?
Overview
This study investigated the phenomenon of bounded empathy and aimed to establish the role
of the mirror neuron system in prejudice. We asked whether actions and emotional reactions
of ingroup members are processed differently than those of outgroup members. We measured
mirror neuron system activation and the experience of vicarious emotions with the EEG while
participants saw videos of ingroup and outgroup members performing actions and expressing
emotions. We predicted that the mirror neuron system would be more active when the
participants observe ingroup members than when they observe outgroup members, and
further, that they would feel more vicarious emotions for ingroup members than for outgroup
members. In addition we expected that ingroup favouritism would be negatively correlated
with, both, mirror neuron system activation and vicarious emotions in response to outgroup
21
members. Thus, this study suggested that the MNS is less responsive to outgroups, and that
this reduction of mirror MNS activation, and the resulting lack of empathy, are at least one of
the reasons for prejudice.
Method
Participants
The original sample consisted of 30 right handed (assessed through self report)
university students who were recruited from the University of Scarborough subject pool, and
who participated in the study for course credit. Two participants were excluded due to a
technical malfunction in the EEG system and another 7 participants had to be excluded due to
excessive movement artifacts that resulted in an inability to obtain sufficient EEG data. As a
result we included 21 participants in our final sample. Ten males and 11 females participated;
5 of them where white, 4 East Asian and 12 South Asian. The participants ranged in age from
18 to 23 Years (M= 18.86, SD= 1.23).
Procedure
Participants were told that the study’s purpose was to investigate the neural
underpinnings of actions and emotions. Participants read and signed an informed consent
sheet and were then fitted with and electrode cap for EEG recording. EEG was recorded while
the participants watched two sets of videos. The first set of videos showed a variety of
ingroup and outgroup members performing a simple action. The second set of videos showed
ingroup and outgroup members displaying basic emotions. After watching each set, the
participants were asked to perform the action or to display the emotions respectively. After
completion of this task, EEG recording stopped. To control for individual differences we,
then, administered several measures related to ingroup favouritism, self-other overlap, and
empathy. Finally the participants were thanked and debriefed.
22
Stimulus Materials
The video sets of ingroup and outgroup members performing actions and expressing
emotions served as the independent variable. For the purpose of this study I defined ingroup
as people who share the participant’s ethnic identity, and outgroup as people who do not. The
first set’s content was action (action block), with participants seeing and performing specified
actions. Specifically, participants observed and performed the action of repeatedly grabbing a
glass of water, lifting it up, drinking a small amount of the water, and putting it down. The
second set (emotion block) was about emotions, with participants seeing and feeling sadness
and happiness.
Each set consisted of three experimental conditions - the ingroup-, the outgroup-, and
the self-condition. In the outgroup condition the participant saw four different actors for each
outgroup. Thus, for example, a white participant would see four different black actors each for
20 seconds followed by four different East Asian actors, and four different South Asian
actors. The videos showed the actors sitting on a table in front of a white wall, either
performing the action or expressing an emotion depending on set. In the ingroup condition,
participants saw four different ingroup member, each for 20 seconds, acting or expressing
sadness and happiness. To ensure that every participant indeed saw videos of ingroup
members I presented videos depicting people with a South Asian, East Asian, Caucasian, and
African ethnic background. The depicted persons were male students of the University of
Toronto and, therefore, had approximately the same age but not always the same sex as the
participants. Each person was displayed for twenty seconds. In order to ensure enough clean
EEG data for the mu rhythm analysis, in the action set, participants observed and acted twice.
Consequently we obtained 160 seconds of EEG data during the self action condition and the
ingroup action condition and a total of 480 seconds during the outgroup action condition with
160 seconds for each ethnic outgroup. In the emotion conditions we obtained 80 seconds of
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EEG data during the self conditions, 80 seconds during the ingroup conditions and 240
seconds of during the outgroup conditions with 80 seconds during each of the different ethnic
outgroups. All ingroup and outgroup videos alternated in random order.
Before participants saw the ingroup and outgroup videos, they saw 160 seconds of
white noise (white noise condition). The data collected during the white noise condition was
used as the baseline of mirror neuron system activation and anterior alpha asymmetry during
rest.
At the end of each of the video sets, the participants were asked to perform the action or
display the emotions themselves (self condition). During this condition participants repeatedly
grabbed the glass of water in front of them with their right hand, brought it to their mouth, and
took a little sip; then they put the glass back to its former place. To ensure correct execution,
they were asked to remember how the actors did the exact same action and to try to do it in
the same way and same pace. In the emotion conditions participants had to either feel sad feel
happy, depending on block. They were also asked to express the emotion as naturally as
possible. To facilitate the experience of the emotions, participants completed an emotion
induction exercise, which consisted of a series of instructions aimed to elicit vivid memories
of past sad and happy events, respectively. For example, participants saw the following
instruction: “Please think about a situation in you past, which made you feel very sad/happy.
Imagine the situation as vividly as you can“. After completion of the exercise participants
tried to feel the emotion for 80 seconds while they were looking at a blank computer screen.
The action block always proceeded the emotion block and in each block the self
conditions appeared at the end of the block so that the participants could model their
performance after the videos. To ensure that participants attended the video throughout the
whole session, they performed a control task during all conditions except during the white
noise and self conditions. In this task, the videos stopped between 2 and 5 times and the
24
screen turned black for 1second. Participants were asked to count how many times the black
screen appeared and to indicate the number of such pauses at the end of the condition.
Measures
Measures of ingroup favouritism. After completion of the EEG measurement, we gave
the participants two measures of ingroup favouritism. First, we implicitly measured group
bias with the Black-White evaluative Implicit Association Test (IAT) (Greenwald, Ghee, &
Schwartz (1998) – a computer-administered reaction time test of implicit associations with
race. In this task, participants were instructed to categorize photographs of Black and White
faces and positive and negative concepts. During one block, participants were asked to press
the same button for Black faces and negative words and for White faces and positive word
(compatible block). During a second block White faces were allocated to the same button as
negative words, and Black faces to the same button as positive words (incompatible
condition). We chose the IAT because it is a widely used and reliable (Greenwald, Nosek&
Banaji, 2003) measure of implicit race bias.
Modern Racism Scale. In addition to implicit racism with the IAT we measured
explicit racism with the modern racism scale (MRS) (McConahay, Hardee, & Batts, 1981).
The MRS is a valid measure of modern racism (McConahay, 1983) a construct that describes
a subtitle form of racism that combines racist feelings with abstract values, such as justice and
order. Modern racists believe that discrimination no longer exists and that Blacks demand
more than they deserve (Henry & Sears, 2002).
Measure of self other overlap. In order to measure the degree of overlap of the
self and the different outgroups, the participants were asked to complete the Inclusion of
Others in the Self Scale (IOS) (Aron, Aron, & Smollan, 1992). In the IOS Scale, respondents
select the overlapping circles that best describes their relationship from a set of diagrams each
25
representing different degrees of overlap of two circles. For every group, South Asian, East
Asian, Caucasian and Black, the participants had to choose one of seven such depictions that
best illustrates their relationship with the group.
Measures of Empathy. To measure individual trait differences in empathy, we
administered the Empathy Quotient (Baron-Cohen, & Wheelwright, 2004). This measure is a
questionnaire that taps cognitive empathy and emotional reactivity to others (Lamm, Batson,
Decety, 2007), and was shown to be a valid and reliable measure of empathy, both, in a
clinical sample of autistic patients and in healthy individuals (Lawrence, Shaw, Baker, Baron-
Cohen, & David, 2004). The capacity for emotional perspective taking was assessed with the
Mind in the Eyes Test (Baron-Cohen, Jolliffe, Mortimore, & Roberston, 1997). In this test,
the participant is presented pictures of the eye-region of different people. They then have to
choose which of four one word descriptions of psychological states best describes what the
person on the picture is thinking or feeling. Performance on this task is an indicator of the
participant’s social sensitivity and is said to be an advanced test of theory of mind (Baron-
Cohen, et al., 1997)
EEG data acquisition and processing. To measure mu rhythm, we recorded the EEG
from 64 Ag/AgCl sintered electrodes embedded in a stretch-lycra cap with a high-density
amplifier and a sampling frequency of 512 Hz. The electrodes where positioned according to
the five percent (10 – 5) electrode system, which is an extension of the 10-20 system to
accommodate larger numbers of electrodes (Oostenveld & Praamstra, 2001). The EEG was
digitized at 512 Hz using ASA acquisition hardware (Advanced Neuro Technology,
Enschede, the Netherlands) with an average earlobe reference. Vertical eye movements
(VEOG) were monitored using a supra-to sub-orbital bipolar montage and the EEG was later
corrected for VEOG with the SOBI procedure (Belouchrani, Meraim, Cardoso, & Moulines,
1997). During recording, the impedances were kept below 10 Kohm to ensure a clear and
26
strong EEG signal. Since the mu frequency band overlaps with the posterior alpha band –
oscillations in the same frequency band as mu due to effects of attention – it is possible that
recordings from posterior central areas might be contaminated by these alpha waves
(Oberman, et al., 2007). To avoid this, we removed the first and last 10 seconds from each
EEG data block. Following we created 75% overlapping epochs of 2 seconds (using a
Hamming window) throughout the conditions and applied fast Fourier transforms in the 8-13,
8-11, 11-13, and 13-15 band passes to these epochs.
Results
The objective of our study was to investigate the possibility of bounded empathy: That
empathy relates to feelings for the ingroup, but not the outgroup. We examined the mirror
neuron system’s role in prejudice and tested whether the mirror neuron system is less active in
response to outgroup members than ingroup members, and whether this is reflected in
differences in vicarious emotions as measured by anterior frontal asymmetries. We therefore
induced empathy by having our participants observe in- and outgroup members acting and
feeling emotions and measured correspondent EEG activity.
Mu suppression
To measure mu suppression we calculated the ratio of the mu power (EEG
bands 8-13, 8-11, 11-13, 13-15 and 15-18) during the self, ingroup and outgroup condition
relative to the white noise control condition. By looking at ratio scores, we could control for
individual differences in scalp thickness (Oberman, et al., 2007). We log transformed the ratio
scores in order to normalize the data. As a result we obtained positive and negative values,
where positive means enhancement of mu rhythm – less mirror neuron activity- and negative
means suppression of mu rhythm – more mirror neuron activity. Although we obtained data
27
from multiple electrodes across the scalp, we only looked at C3, Cz, and C4 since mu rhythm
is normally measured over the sensorimotor cortex (Oberman, et al.,2007).
None of these electrodes showed significant mu suppression during neither of the
experimental conditions. However, we found a significant decline in mirror neuron activity in
the 13-15 band during the self condition relative to the white noise control condition (t (C3) =
3.433, p = .003; t (C4) = 1.765, p = ns; t (CZ) = 2815, p = .011). Mu basically represents
sensory motor neurons being a rest and, thus, an increase in mu, as represented in our data,
indicates, that sensory motor neurons were less active when participants acted then when they
sat still. Since actions cannot be performed without activity of the respective neurons, the
obtained mu rhythm data are puzzling and cannot be interpreted.
Anterior alpha asymmetry
To assess approach and avoidance related emotions we obtained the alpha band power
at a left (F8) and a right (F7) frontal electrode site for each condition. Because the alpha
power values are usually positively skewed (Allen, Coan, & Nazarian, 2004), we log
transformed them to normalize the distributions. Following, to control for individual
differences in overall alpha power, we computed a log difference score for each of the
conditions (log right alpha power minus log left alpha power). Alpha power is highest when
the underlying neurons are at rest, thus we took alpha power as an index of the inverse of
cortical activity. A lower alpha power in the right hemisphere signals positive, approach
related emotions, and lower alpha power in the left hemisphere signals negative, avoidance
related emotions. Consequently, when creating the difference score lower scores indicate
relatively greater left fontal activity, or more negative emotions.
To investigate the specific effects of the experimental conditions on relative alpha
power, we ran several t-tests. In the self conditions, participants showed marginally
28
significantly lower scores, (t (20) = 1.91, p = .07), when they experienced sadness (M= -0.05,
SD= 0.16) than when they experienced happiness (M= -0.01, SD=0.15), indicating that the
manipulation induced the intended emotions. Moreover, asymmetry during the experience of
sadness was marginally significantly different from zero, (t (20) = -1.9, p = .07).
To test for vicarious emotions, we compared participants’ relative alpha power in the
ingroup and outgroup condition with their relative alpha power during the self condition. We,
also, looked at a specific case of the outgroup condition – the black condition. When looking
at frontal asymmetry related to sadness, asymmetry scores for the self (M=-0.07 SD=0.17)
and the ingroup condition (M=-0.03 SD=0.11) where not significantly different from each
other (t (20) = 1.4, p = .17), nor were Asymmetry scores for the self (M=-0.07 SD=0.17) and
the outgroup condition (M=-0.03 SD=0.15). Thus participants showed the same reaction when
feeling sadness and when observing ingroup and outgroup members expressing sadness.
However, this was not true for the black outgroup. Participants showed significantly higher
scores when they saw Blacks expressing sadness (-0.01, SD=0.16) then when feeling sad
themselves (M=-0.07 SD=0.17) (t (20) = 2.106, p = .048). There were no significant
differences between the ingroup and outgroup condition, the ingroup and black condition and
the outgroup and black condition. A trend analysis on asymmetry difference scores for the
self, ingroup, outgroup and black conditions revealed that participants showed a linear trend
(F=5.184, p = .03) with the strongest left frontal asymmetry during the self condition,
followed by the outgroup and ingroup condition and finally the black condition (Please see
figure 2 for a depiction of these results). Thus participants seem to feel saddest when acting
and experiencing sadness themselves, they feel less sad when they observe an ingroup
member or an outgroup member expressing sadness but they do feel a certain degree of
vicarious sadness. Contrary, they do not seem to feel vicarious sadness towards Blacks. Since
alpha power is relatively consistent within individual participants and sites (Allen, et al.,
29
2004) an expected, relative alpha power for all conditions correlate highly with each other (all
correlations higher than .62with p<0.09). The same analysis conducted at posterior sites P3
and P4 revealed the opposite pattern. We found significant differences between the ingroup
condition and the self condition and the ingroup condition and the outgroup condition, but no
difference between the black condition and the self condition. However, relative alpha power
of the posterior sites did not correlate with each other. This lack of congruence, and the fact
that posterior alpha activity is generally seen as related more to attention than emotions,
questions the relevance of these findings. The mismatch between the posterior and anterior
data, illustrates the topographical specificity of the effects for anterior cortical activity.
Contrary to the data with sadness, anterior alpha asymmetry was not significant in any
of the happy conditions. Neither was anterior alpha asymmetry significantly different from
zero during the experience of self-happiness nor did it reveal any experience of vicarious
emotions in the ingroup and outgroup condition.
Figure 2: Anterior alpha asymmetry cores during the two emotion conditions (Sad, Happy)
for ingroup, self and black. Participants showed significantly lower anterior alpha asymmetry
scores during the self condition than during the Black condition. This indicates relatively
more negative, avoidance related emotions during the experience of sadness than when
observing the black outgroup. The ingroup condition did not significantly differ from the self
condition.
30
Behavioural measures
Correlation with empathy. The hypothesis of bounded empathy is further supported by
the pattern of correlations observed between alpha power and empathy. Anterior alpha
asymmetry in response to sad ingroup members correlated negatively with participants’ scores
on the Empathy Quotient Scale. Thus the more empathy the participant was capable to
experience in general, the more vicarious sadness he or she felt towards ingroup members (r =
-.414, p<.062). This was not true, however, when the participants observed Blacks – there was
no correlation between frontal asymmetry in response to sad Blacks and trait empathy (r =
0.068, ns) (See table 1). These findings suggest that empathy is generally extensible in that
people can become experts in empathy. However, this expertise does not extend to outgroup
members.
Table 1: Correlations between anterior alpha asymmetry scores and the measures of ingroup
favouritism and empathy. Alpha asymmetry scores during the sad condition correlated
marginally significantly negatively with trait empathy (EQ) (p<.65, correlation bolded in
table) for the observation of sad ingroup members but not sad outgroup members.
Correlation with ingroup favouritism - IAT, MRS and IOS. The acquired IAT reaction
times where treated according to Greenwald et al. (2003), thus a single d- score was computed
Measures
Condition IAT MRS EQ RME Ingroup
Sad -0.215 0.203 -0.414 0.354
Happy 0.09 0.309 -0.221 0.249
Black
Sad 0.257 0.345 0.068 0.216
Happy -0.243 0.097 -0.361 0.191
Outgroup
31
for each participant. A positive d-score indicates that the participant has stronger associations
between Blacks and negative words. The mean d-score was .1615 (SD= 0.213). D-scores
were significantly different from zero (t= 3.470, p = .002.) This replicates the general finding
that non-black participants have a stronger association between Blacks and negative words
and Whites and positive words a finding that indicates implicit bias against Blacks
(Greenwald, et al., 1998).
Contrary to our expectations, IAT scores did not correlate significantly with either of
our main measures of brain activity. In addition, none of our other measures of intergroup bias
correlated significantly with anterior alpha asymmetry. Hence, our hypotheses on the
relationship between vicarious emotions towards outgroups and prejudice were not confirmed.
Since the IOS, the MRS and the IAT are reliable measures of ingroup favouritism and
perceived similarity (Aron, Aron, & Smollan, 1992, Greenwald, Nosek& Banaji, 2003,
McConahay, 1983) this suggests that individual differences in prejudice and the subjective
closeness to outgroup do not influence the experience of vicarious emotions towards these
groups.
Discussion
Findings and implications
The aim of this study was to investigate bounded empathy as one of the underlying factors for
prejudice. First, we expected that the mirror neuron system would be less active in response to
outgroup members than ingroup members, and that this lack in mirror neuron system
activation will result in the experience of weaker vicarious emotions. Further we explored
how mirror neuron activity and the experience of vicarious emotions are influenced by
individual differences in trait empathy and level of prejudice.
32
Our findings support these hypotheses to some extent. However, methodological
problems left us unable to measure mu-rhythm suppression and, thus, we could not
investigate our hypotheses about mirror neuron activity. The analysis of the mu-band data
revealed no significant mu suppression in any condition. This lack in mu suppression suggests
that the motor neurons were inactive while participants moved their arms, hands and mouth.
There can be no movement without motor neuron activity. Still, our results show that the
participants moved without their motor neurons being active; hence, there must be a
measurement error. Unfortunately, our inability to replicate the basic relationship between mu
suppression and action makes it impossible to investigate mirror neuron activity.
Using anterior frontal asymmetry as a measure of vicarious emotions, we found that
participants felt weaker or less vicarious sadness in response to sad, black outgroup members.
When participants were confronted with sad ingroup members their frontal alpha patterns
where similar to when they experienced sadness themselves. According to the perception
action hypothesis of empathy, this was the case because the mere observation of sadness in
ingroup members activated the same brain structures involved in the experience of sadness.
Since anterior alpha power patterns in response to sad Blacks differed from the ones observed
during the experience of sadness, participants did not feel as strong vicarious sadness for
Blacks as for their ingroup. These findings suggest that empathy is bounded to ingroup
members, and to certain outgroups, but excludes the black outgroup. Since the finding of
bounded empathy only applied to the black outgroup and not to outgroups in general (i.e.
Whites, South Asians and East Asians), the question of why specifically Blacks do not elicit
an empathic reaction to other groups remains. Similarity could be an important factor that
distinguishes Blacks from the other groups. Recall that, according to Fiske’s et al. (2002)
Stereotype Content Model, each group can be defined by two dimensions: warmth and
competence. Groups that score low on both dimensions such as homeless and drug addicts are
33
perceived as extremely dissimilar to oneself and even as less than human. Blacks score lower
on both, warmth and competence then our other three groups (Fiske, et al., 2002), thus they
are likely perceived as being less similar to the participants. This perceived dissimilarity
might make Blacks an extreme outgroup leaving participants unable to empathize with them.
When looking at the happy conditions, anterior alpha asymmetry was not
significant in any of the conditions. This lack could result from an inadequate
operationalization of happiness. In the happy self condition, participants had to remember a
happy situation from their own experiences and try to re-experience the emotions they felt
during this event. Research on frontal asymmetries suggests that this manipulation might fail
because it is focussed on memory and thus elicits emotions that are past oriented. However,
because anterior alpha asymmetries are sensitive to approach related emotions they tend to be
sensitive to future oriented positive emotions during anticipation of positive outcomes
(Davidson, 2004, Gable, & Harmon-Jones, 2008). Therefore, future studies should investigate
alpha asymmetry while participants anticipate and see others anticipating a positive event.
Our second hypothesis predicted that individual differences in empathy and prejudice
would have an impact on the experience of vicarious emotion towards outgroups. This was
only confirmed for empathy. Participants with higher levels of trait empathy showed more left
anterior alpha activity in response to sad ingroup members. However, higher levels of trait
empathy had no effects on anterior alpha activity in response to sad Blacks. Thus participants
did not experience vicarious sadness for Blacks even when they generally were extremely
receptive to other’s emotions. It seems as if the ability to empathize is expandable but this
stops when it comes to Blacks.
Our findings indicate that people generally empathize less with Blacks and this might
lead to prejudice because it creates a barrier that blocks understanding and smooth
communication. As noted above, enhancing empathy towards an outgroup reduces prejudice
34
levels (Galinsky, & Moskowitz, 2000) thus a reduction of empathy might be a risk factor for
prejudice. This risk factor enhances the probability for prejudice, but people might be able to
compensate for the lack of empathy through cognitive perspective taking, which is a top down
process and does not rely on bottom up information from vicarious emotions (Preston, &
deWaal, 2002). In our society, in which expressing prejudice is socially undesirable (Devine,
Montheith, Zuwerink, & Elliot, 1991), people will be motivated to do so. Our sample
consisted of university students in one of North America’s most diverse cities studying at a
very diverse campus. Hence, it is likely that these students adopted strategies to compensate
for reduced empathy towards outgroup members. Additional research is necessary to
conclusively determine the relationship between empathy towards outgroups and prejudice
conclusively.
Limitations and Future Directions
We obtained two measures of trait empathy: the Mind in the Eyes task and the empathy
quotient, and one measure of state empathy: anterior alpha asymmetry. Although, anterior
alpha asymmetry has been shown to correlate with subjective self reported emotions
(Davidson, 2004), we did not include a self report measure of vicarious emotions, state
empathy or mood. Future research should include such measures to allow a comparison
between the subjective experience and anterior alpha asymmetries and to capture potential
differences between these two measures. Moreover, since anterior alpha asymmetries cannot
inform us on the specific nature of the approach or avoidance motivation, self report measures
could provide interesting additional information. For example, since there are different stages
in empathy we cannot tell whether we measured the initial vicarious emotions (i.e. sadness in
response to the observation of sadness) or the result of higher cognitive processing (i.e. the
motivation to avoid the stimulus in order to reduce personal distress).
35
Another important extension to our research would be to investigate the possible
positive effects of empathy enhancing factors such as fostering fondness, perceived
familiarity and similarity. Theoretically these factors should make the target a more likely
object of empathy, and should thus enhance the experience of vicarious emotions. This
extension would also enable researchers to disentangle the different reasons for why blacks
are perceived differently than other outgroups. Do they fail to elicit empathy due to their
dissimilarity, unfamiliarity or because they are disliked more?
Conclusions
To our knowledge, this study is the first that directly demonstrates reduced empathy towards
an outgroup. Although, others did show a connection between empathy and prejudice by
showing that empathy reduces prejudice (Galinsky, & Moskowitz, 2000) and that people
show less helping behavior towards outgroups (Dovidio, et al., 1997), these studies lack a
direct measure of empathy. By applying an objective measure of empathy based on neural
signals – anterior alpha asymmetries – this study could directly measure empathy towards
outgroups. Thus, we could establish that empathy is bounded to ingroup members and that at
least extreme outgroups, such as blacks, are excluded from our circle of empathy.
The fact that neither general ability to empathize nor individual differences in intergroup bias
had an effect on empathy towards Blacks further suggest that the bounds of empathy are
relatively fixed.
Given the positive effect of empathy such as the facilitation of social understanding and
prosocial behaviour, helping behaviour, and the inhibition of aggression and antisocial
behaviour, the lack of vicarious emotions towards blacks draws a rather dark picture.
However, taking into account the current findings, promoting perspective taking is a
promising candidate for a possible remediation. Instead of trying to equal our reactions
36
towards outgroups to those towards ingroups – a distinction that might be unchangeable - this
strategy aims to include outgroup members into our ingroup. This could create feeling of
common humanness and could help us remember Shylock’s words that all of us bleed, laugh
and die, no matter our colour, race, or religion.
37
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