The other-race effect for face perception: an event-related potential study

Do neural correlates of face expertise vary with task demands? Event-related potential correlates of own- and other-race face inversion

We are typically more accurate at remembering own- than other-race faces. This “own-race bias” has been suggested to result from enhanced expertise with and more efficient perceptual processing of own-race than other-race faces. In line with this idea, the N170, an event-related potential correlate of face perception, has been repeatedly found to be larger for other-race faces. Other studies, however, found no difference in N170 amplitude for faces from diverse ethnic groups. The present study tested whether these seemingly incongruent findings can be explained by varying task demands. European participants were presented with upright and inverted European and Asian faces (as well as European and Asian houses), and asked to either indicate the ethnicity or the orientation of the stimuli. Larger N170s for other-race faces were observed in the ethnicity but not in the orientation task, suggesting that the necessity to process facial category information is a minimum prerequisite for the occurrence of the effect. In addition, N170 inversion effects, with larger amplitudes for inverted relative to upright stimuli, were more pronounced for own- relative to other-race faces in both tasks. Overall, the present findings suggest that the occurrence of ethnicity effects in N170 for upright faces depends on the amount of facial detail required for the task at hand. At the same time, the larger inversion effects for own- than other-race faces occur independent of task and may reflect the fine-tuning of perceptual processing to faces of maximum expertise.

Early visual ERP sensitivity to the species and animacy of faces

Assessing the agency of potential actors in the visual world is a critically important aspect of social cognition. Adult observers are generally capable of distinguishing real faces from artificial faces (even allowing for recent advances in graphics technology and motion capture); even small deviations from real facial appearance can lead to profound effects on face recognition. Presently, we examined how early components of visual event-related potentials (ERPs) are affected by the "life" in human faces and animal faces. We presented participants with real and artificial faces of humans and dogs, and analyzed the response properties of the P100 and the N170 as a function of stimulus appearance and task (species categorization vs. animacy categorization). The P100 exhibited sensitivity to face species and animacy. We found that the N170's differential responses to human faces vs. dog faces depended on the task participants' performed. Also, the effect of species was only evident for real faces of humans and dogs, failing to obtain with artificial faces. These results suggest that face animacy does modulate early components of visual ERPs-the N170 is not merely a crude face detector, but reflects the tuning of the visual system to natural face appearance.

Species-specific effects of pigmentation negation on the neural response to faces

Face processing is limited in scope as a function of experience - discrimination ability and face-specific behavioral effects are reduced in out-group faces. Nonetheless, other-species faces phylogenetically close to our own may be processed by similar mechanisms as human faces. Presently, we asked whether or not the well-known effect of contrast-negation on face recognition (Galper, 1970) was exclusive to human faces or generalized to monkey faces. Negation disrupts face pigmentation substantially, allowing us to examine species-specific use of surface cues as a function of expertise. We tested adult observers behaviorally and electrophysiologically: participants completed a 4AFC discrimination task subject to manipulations of face species and independent negation of image luminance and image chroma, and the same stimuli were used to collect event-related potentials in a go/no-go task. We predicted that expertise for human faces would lead to larger deleterious effects of negation for human faces in both tasks, reflected in longer RTs for correct responses in the discrimination task and species-specific modulation of the N170 and P200 by contrast-negation. Our results however, indicate that behaviorally, luminance and chroma negation affect discrimination performance in a species-independent manner, while similar effects of contrast-negation effects are evident in each species at different components of the ERP response.

How experience shapes memory for faces: an event-related potential study on the own-age bias

Young adults more accurately remember own-age than older faces. We tested whether this own-age bias (OAB) is reduced by increased experience. Young experts (geriatric nurses) and controls performed a recognition experiment with young and old faces. Critically, while control participants demonstrated better memory for young faces, no OAB was observed in the experts. Event-related potentials revealed larger N170 and P2 amplitudes for young than old faces in both groups, suggesting no group differences during early perceptual processing. At test, N250 repetition effects were more anteriorily distributed for own- than other-age faces in control participants, whereas experts showed no corresponding effects. A larger late positive component (LPC) for old than young faces was observed in controls, but not in experts. Larger LPCs may reflect prolonged stimulus processing compromising memory retrieval. In sum, experience with other-age faces does not affect early perceptual processing, but modulates later stages related to memory retrieval.

Implicit conditioning of faces via the social regulation of emotion: ERP evidence of early attentional biases for security conditioned faces

Not much is known about the neural and psychological processes that promote the initial conditions necessary for positive social bonding. This study explores one method of conditioned bonding utilizing dynamics related to the social regulation of emotion and attachment theory. This form of conditioning involves repeated presentations of negative stimuli followed by images of warm, smiling faces. L. Beckes, J. Simpson, and A. Erickson (2010) found that this conditioning procedure results in positive associations with the faces measured via a lexical decision task, suggesting they are perceived as comforting. This study found that the P1 ERP was similarly modified by this conditioning procedure and the P1 amplitude predicted lexical decision times to insecure words primed by the faces. The findings have implications for understanding how the brain detects supportive people, the flexibility and modifiability of early ERP components, and social bonding more broadly.

Putting a face in its place: in- and out-group membership alters the N170 response

Two mechanisms have been proposed to account for the difficulty in recognizing faces of other racial groups (the other-race effect; ORE): perceptual expertise and social cognitive factors. Focusing on the social cognitive factors alone, we manipulated in-group and out-group memberships based on two social categories (nationality and university affiliation), and controlled for perceptual expertise by testing Caucasian participants with Caucasian faces only. Using event-related potentials (ERPs) and focusing on the N170, a brain electrical component sensitive to faces, we provide for the first time strong support for the social cognitive influence on face processing within 200 ms. After participants learned the social categories, the N170 latency differentiated between double in-group and double out-group faces, taking longer to process the latter. In comparison, without group memberships, there was no difference in N170 latency among the faces. These results are consistent with recent findings of behavioral and imaging research, providing further support for the social cognitive model and its potential for understanding ORE.

Electrophysiological correlates of processing own- and other-race faces

Most adults have more experience in identifying faces of their own race than in identifying faces from another race, and thus may be considered as own-race face experts. This effect was investigated by recording and analyzing ERPs as well as induced gamma oscillations. The race modulation occurred post the stage of structural processing revealed by N170. Larger P2 component and induced gamma activity for own-race than other-race faces could be associated with more elaborate processing on the basis of configural computation due to more experience that we have for own-race faces.

Structural face encoding: How task affects the N170's sensitivity to race

The N170 event-related potential (ERP) component differentiates faces from non-faces, but studies aimed at investigating whether the processing indexed by this component is also sensitive to racial differences among faces have garnered conflicting results. Here, we explore how task affects the influence of race on the N170 among White participants. N170s were larger to ingroup White faces than outgroup Black faces, but only for those required to attend to race, suggesting that attention to race can result in deeper levels of processing for ingroup members. Conversely, N170s were larger to Black faces than White faces for participants who attended to the unique identity of the faces, suggesting that attention to identity can result in preferential recruitment of cognitive resources for outgroup members. Taken together, these findings suggest that race can differentially impact face processing at early stages of encoding, but differences in processing are contingent upon one's goal state.

Rapid social perception is flexible: approach and avoidance motivational states shape P100 responses to other-race faces

Research on person categorization suggests that people automatically and inflexibly categorize others according to group memberships, such as race. Consistent with this view, research using electroencephalography (EEG) has found that White participants tend to show an early difference in processing Black versus White faces. Yet, new research has shown that these ostensibly automatic biases may not be as inevitable as once thought and that motivational influences may be able to eliminate these biases. It is unclear, however, whether motivational influences shape the initial biases or whether these biases can only be modulated by later, controlled processes. Using EEG to examine the time course of biased processing, we manipulated approach and avoidance motivational states by having participants pull or push a joystick, respectively, while viewing White or Black faces. Consistent with previous work on own-race bias, we observed a greater P100 response to White than Black faces; however, this racial bias was attenuated in the approach condition. These data suggest that rapid social perception may be flexible and can be modulated by motivational states.

Neural processing of race by individuals with Williams syndrome: do they show the other-race effect? (And why it matters)

Williams syndrome (WS) is a genetic condition with a distinctive social phenotype characterized by excessive sociability accompanied by a relative proficiency in face recognition, despite severe deficits in the visuospatial domain of cognition. This consistent phenotypic characteristic and the relative homogeneity of the WS genotype make WS a compelling human model for examining genotype-phenotype relations, especially with respect to social behavior. Following up on a recent report suggesting that individuals with WS do not show race bias and racial stereotyping, this study was designed to investigate the neural correlates of the perception of faces from different races, in individuals with WS as compared to typically developing (TD) controls. Caucasian WS and TD participants performed a gender identification task with own-race (White) and other-race (Black) faces while event-related potentials (ERPs) were recorded. In line with previous studies with TD participants, other-race faces elicited larger amplitude ERPs within the first 200 ms following the face onset, in WS and TD participants alike. These results suggest that, just like their TD counterparts, individuals with WS differentially processed faces of own-race versus other-race, at relatively early stages of processing, starting as early as 115 ms after the face onset. Overall, these results indicate that neural processing of faces in individuals with WS is moderated by race at early perceptual stages, calling for a reconsideration of the previous claim that they are uniquely insensitive to race.

Brain potentials show rapid activation of implicit attitudes towards young and old people

While previous behavioural research suggests that attitudes, for example towards elderly people, may be activated automatically, this type of research does not provide information about the detailed time-course of such processing in the brain. We investigated the impact of age related attitude information in a Go/NoGo association task that paired photographs of elderly or young faces with positive or negative words. Event related brain potentials showed an N200 (NoGo) component, which appeared earlier in runs which required similar responses for congruent stimulus pairings (e.g. respond to pictures of elderly faces or negative words) than for incongruent pairings (e.g. respond to elderly faces or positive words). As information processing leading to a certain attitude must precede differential brain activity according to the congruence of the paired words and faces, we show that this type of information is activated almost immediately following the structural encoding of the face, between 170 and 230 ms after onset of the face.

Electro-cortical implicit race bias does not vary with participants' race or sex

Earlier research found evidence for electro-cortical race bias towards black target faces in white American participants irrespective of the task relevance of race. The present study investigated whether an implicit race bias generalizes across cultural contexts and racial in- and out-groups. An Australian sample of 56 Chinese and Caucasian males and females completed four oddball tasks that required sex judgements for pictures of male and female Chinese and Caucasian posers. The nature of the background (across task) and of the deviant stimuli (within task) was fully counterbalanced. Event-related potentials (ERPs) to deviant stimuli recorded from three midline sites were quantified in terms of mean amplitude for four components: N1, P2, N2 and a late positive complex (LPC; 350-700 ms). Deviants that differed from the backgrounds in sex or race elicited enhanced LPC activity. These differences were not modulated by participant race or sex. The current results replicate earlier reports of effects of poser race relative to background race on the LPC component of the ERP waveform. In addition, they indicate that an implicit race bias occurs regardless of participant's or poser's race and is not confined to a particular cultural context.

Thatcherization impacts the processing of own-race faces more so than other-race faces: an ERP study

It has been suggested that differential use of configural processing strategies may underlie racially based recognition deficits (known as the "other-race effect"). By employing a well-known configural manipulation (Thatcherization, i.e., rotating the eyes and mouth by 180°), we aimed to demonstrate, electrophysiologically, that configural processing is used to a greater extent when viewing same-race faces than when viewing other-race faces. Face-related event-related potential (ERP) responses were measured for participants viewing normal and Thatcherized faces of their own race (Caucasian) and of another race (African-American). The P1 and N170 components were modulated to a greater extent by Thatcherization for same-race faces, suggesting that the processing of these faces is, in fact, more reliant on configural information than other-race faces. Thatcherization also affected the P250 component more so for same-race faces independently of orientation. The race-dependent effects of Thatcherization as early as P1 suggest that configural encoding may be occurring much earlier than the well-cited N170.

Racial identification modulates default network activity for same and other races

Racial identification shapes self-concept and how people share in and respond to the emotional states of others around them. Prior neuroimaging studies have demonstrated the role of the neural default network in self-referential and empathic processing. However, how racial identification affects neural processing of social information remains unknown. Here, we examined the effect of racial identification on neural response related to social perception among African American and Caucasian American individuals using functional magnetic resonance imaging. Our results demonstrate that degree of racial identification predicts activity within cortical midline structures of the default network in response to viewing racial ingroup, relative to outgroup members, and activity within the medial temporal lobe subsystem of the default network in response to viewing racial outgroup, relative to ingroup members. Broadly, our findings suggest that the strength of racial identification is associated with differential recruitment of neural and cognitive processes to understand and respond to other people within and outside of one's racial group.

Neural repetition suppression to identity is abolished by other-race faces

Human beings are remarkably skilled at recognizing faces, with the marked exception of other-race faces: the so-called "other-race effect." As reported nearly a century ago [Feingold CA (1914) Journal of Criminal Law and Police Science 5:39-51], this face-recognition impairment is accompanied by the popular belief that other-race faces all look alike. However, the neural mechanisms underlying this high-level "perceptual illusion" are still unknown. To address this question, we recorded high-resolution electrophysiological scalp signals from East Asian (EA) and Western Caucasian (WC) observers as they viewed two EA or WC faces. The first adaptor face was followed by a target face of either the same or different identity. We quantified repetition suppression (RS), a reduction in neural activity in stimulus-sensitive regions following stimulus repetition. Conventional electrophysiological analyses on target faces failed to reveal any RS effect. However, to fully account for the paired nature of RS events, we subtracted the signal elicited by target to adaptor faces for each single trial and performed unbiased spatiotemporal data-driven analyses. This unique approach revealed stronger RS to same-race faces of same identity in both groups of observers on the face-sensitive N170 component. Such neurophysiological modulation in RS suggests efficient identity coding for same-race faces. Strikingly, OR faces elicited identical RS regardless of identity, all looking alike to the neural population underlying the N170. Our data show that sensitivity to race begins early at the perceptual level, providing, after nearly 100 y of investigations, a neurophysiological correlate of the "all look alike" perceptual experience.

Electrophysiological correlates of processing faces of younger and older individuals

The 'own-age bias' in face processing suggests that the age of a face constitutes one important factor that influences attention to and memory for faces. The present experiment investigated electrophysiological correlates of processing faces of younger and older individuals. Younger participants were presented with pictures of unfamiliar younger and older faces in the context of a gender categorization task. A comparison of event-related potentials showed that early components are sensitive to faces of different ages: (i) larger positive potential peaking at 160 ms (P200) for older than younger faces at fronto-central electrodes; (ii) larger negative potential peaking at 252 ms (N200) for younger than older faces at fronto-central electrodes; (iii) larger negative-going deflection peaking at 320 ms (N250) for younger than older faces at occipito-temporal electrodes; and (iv) larger late positive potential peaking at 420 ms (LPP 420) for older than younger faces at parietal and other electrodes. We discuss similarities between the present study and a previously published study of faces of different races as suggesting involvement of comparable electrophysiological responses when differentiating between stimulus categories.

Early Neural Markers of Implicit Attitudes: N170 Modulated by Intergroup and Evaluative Contexts in IAT

The Implicit Association Test (IAT) is the most popular measure to evaluate implicit attitudes. Nevertheless, its neural correlates are not yet fully understood. We examined event related potentials (ERPs) in response to face- and word processing while indigenous and non-indigenous participants performed an IAT displaying faces (ingroup and outgroup members) and words (positive and negative valence) as targets of category judgments. The N170 component was modulated by valence of words and by ingroup/outgroup face categorization. Contextual effects (face–words implicitly associated in the task) had an influence on the N170 amplitude modulation. On the one hand, in face categorization, right N170 showed differences according to the association between social categories of faces and affective valence of words. On the other, in word categorization, left N170 presented a similar modulation when the task implied a negative-valence associated with ingroup faces. Only indigenous participants showed a significant IAT effect and N170 differences. Our results demonstrate an early ERP blending of stimuli processing with both intergroup and evaluative contexts, suggesting an integration of contextual information related to intergroup attitudes during the early stages of word and face processing. To our knowledge, this is the first report of early ERPs during an ethnicity IAT, opening a new branch of exchange between social neuroscience and social psychology of attitudes.

The neural correlates of race

Behavioral analyses are a natural choice for understanding the wide-ranging behavioral consequences of racial stereotyping and prejudice. However, studies using neuroimaging and electrophysiological research have recently considered the neural mechanisms that underlie racial categorization and the activation and application of racial stereotypes and prejudice, revealing exciting new insights. Work that we review here points to the importance of neural structures previously associated with face processing, semantic knowledge activation, evaluation and self-regulatory behavioral control, enabling specification of a neural model of race processing. We show how research on the neural correlates of race can serve to link otherwise disparate lines of evidence on the neural underpinnings of a broad array of social-cognitive phenomena; we also consider the implications for effecting change in race relations.

The role of face shape and pigmentation in other-race face perception: an electrophysiological study

Adult observers generally find it difficult to recognize and distinguish faces that belong to categories with which they have limited visual experience. One aspect of this phenomenon is commonly known as the "Other-Race Effect" (ORE) since this behavior is typically highly evident in the perception of faces belonging to ethnic or racial groups other than that of the observer. This acquired disadvantage in face recognition likely results from highly specific "tuning" of the underlying representation of facial appearance, leading to efficient processing of commonly seen faces at the expense of poor generalization to other face categories. In the current study we used electrophysiological (event-related potentials or ERPs) and behavioral measures of performance to characterize face processing in racial categories defined by dissociable shape and pigmentation information. Our goal was to examine the specificity of the representation of facial appearance in more detail by investigating how race-specific face shape and pigmentation separately modulated neural responses previously implicated in face processing, the N170 and N250 components. We found that both components were modulated by skin color, independent of face shape, but that only the N250 exhibited sensitivity to face shape. Moreover, the N250 appears to only respond differentially to the skin color of upright faces, showing a lack of color sensitivity for inverted faces.

The NimStim set of facial expressions: judgments from untrained research participants

A set of face stimuli called the NimStim Set of Facial Expressions is described. The goal in creating this set was to provide facial expressions that untrained individuals, characteristic of research participants, would recognize. This set is large in number, multiracial, and available to the scientific community online. The results of psychometric evaluations of these stimuli are presented. The results lend empirical support for the validity and reliability of this set of facial expressions as determined by accurate identification of expressions and high intra-participant agreement across two testing sessions, respectively.

The relation between race-related implicit associations and scalp-recorded neural activity evoked by faces from different races

The neural correlates of the perception of faces from different races were investigated. White participants performed a gender identification task in which Asian, Black, and White faces were presented while event-related potentials (ERPs) were recorded. Participants also completed an implicit association task for Black (IAT-Black) and Asian (IAT-Asian) faces. ERPs evoked by Black and White faces differed, with Black faces evoking a larger positive ERP that peaked at 168 ms over the frontal scalp, and White faces evoking a larger negative ERP that peaked at 244 ms. These Black/White ERP differences significantly correlated with participants' scores on the IAT-Black. ERPs also differentiated White from Asian faces and a significant correlation was obtained between the White-Asian ERP difference waves at approximately 500 ms and the IAT-Asian. A positive ERP at 116 ms over occipital scalp differentiated all three races, but was not correlated with either IAT. In addition, a late positive component (around 592 ms) was greater for the same race compared to either other race faces, suggesting potentially more extended or deeper processing of the same race faces. Taken together, the ERP/IAT correlations observed for both other races indicate the influence of a race-sensitive evaluative process that may include early more automatic and/or implicit processes and relatively later more controlled processes.

In-group and out-group membership mediates anterior cingulate activation to social exclusion

Functional magnetic resonance imaging was employed to examine sensitivity to social exclusion in three conditions: same-race, other-race, and self-resembling faces. The anterior cingulate cortex (ACC), specifically the dorsal ACC, has been targeted as a key substrate in the physical and social pain matrix and was hypothesized to regulate activation response to various facial conditions. We show that participants demonstrated greatest ACC activation when being excluded by self-resembling and same-race faces, relative to other-race faces. Additionally, participants expressed greater distress and showed increased ACC activation as a result of exclusion in the same-race condition relative to the other-race condition. A positive correlation between implicit racial bias and activation in the amygdala was also evident. Implicit attitude about other-race faces partly explains levels of concern about exclusion by out-group individuals. These findings suggest that individuals are more distressed and their brain (i.e. neural alarm system) responds with greater activation when being excluded by individuals whom they are more likely to share group membership with.