Ingroup categorization affects the structural encoding of other-race faces: Evidence from the N170 event-related potential

Null effect of anodal and cathodal transcranial direct current stimulation (tDCS) on own- and other-race face recognition

Successful face recognition is important for social interactions and public security. Although some preliminary evidence suggests that anodal and cathodal transcranial direct current stimulation (tDCS) might modulate own- and other-race face identification, respectively, the findings are largely inconsistent. Hence, we examined the effect of both anodal and cathodal tDCS on the recognition of own- and other-race faces. Ninety participants first completed own- and other-race Cambridge Face Memory Test (CFMT) as baseline measurements. Next, they received either anodal tDCS, cathodal tDCS or sham stimulation and finally they completed alternative versions of the own- and other-race CFMT. No difference in performance, in terms of accuracy and reaction time, for own- and other-race face recognition between anodal tDCS, cathodal tDCS and sham stimulation was found. Our findings cast doubt upon the efficacy of tDCS to modulate performance in face identification tasks.

Beyond facial expressions: A systematic review on effects of emotional relevance of faces on the N170

The N170 is the most prominent electrophysiological signature of face processing. While facial expressions reliably modulate the N170, there is considerable variance in N170 modulations by other sources of emotional relevance. Therefore, we systematically review and discuss this research area using different methods to manipulate the emotional relevance of inherently neutral faces. These methods were categorized into (1) existing pre-experimental affective person knowledge (e.g., negative attitudes towards outgroup faces), (2) experimentally instructed affective person knowledge (e.g., negative person information), (3) contingency-based affective learning (e.g., fear-conditioning), or (4) the immediate affective context (e.g., emotional information directly preceding the face presentation). For all categories except the immediate affective context category, the majority of studies reported significantly increased N170 amplitudes depending on the emotional relevance of faces. Furthermore, the potentiated N170 was observed across different attention conditions, supporting the role of the emotional relevance of faces on the early prioritized processing of configural facial information, regardless of low-level differences. However, we identified several open research questions and suggest venues for further research.

Neural timing of the other-race effect across the lifespan: A review

Face race influences the way we process faces, so that faces of a different ethnic group are processed for identity less efficiently than faces of one's ethnic group - a phenomenon known as the Other-Race Effect (ORE). Although widely replicated, the ORE is still poorly characterized in terms of its development and the underlying mechanisms. In the last two decades, the Event-Related Potential (ERP) technique has brought insight into the mechanisms underlying the ORE and has demonstrated potential to clarify its development. Here, we review the ERP evidence for a differential neural processing of own-race and other-race faces throughout the lifespan. In infants, race-related processing differences emerged at the N290 and P400 (structural encoding) stages. In children, race affected the P100 (early processing, attention) perceptual stage and was implicitly encoded at the N400 (semantic processing) stage. In adults, processing difficulties for other-race faces emerged at the N170 (structural encoding), P200 (configuration processing) and N250 (accessing individual representations) perceptual stages. Early in processing, race was implicitly encoded from other-race faces (N100, P200 attentional biases) and in-depth processing preferentially applied to own-race faces (N200 attentional bias). Encoding appeared less efficient (Dm effects) and retrieval less recollection-based (old/new effects) for other-race faces. Evidence admits the contribution of perceptual, attentional, and motivational processes to the development and functioning of the ORE, offering no conclusive support for perceptual or socio-cognitive accounts. Cross-racial and non-cross-racial studies provided convergent evidence. Future research would need to include less represented ethnic populations and the developmental population.

Neural Basis of Prejudice and Prejudice Reduction

Social prejudices, based on race, ethnicity, gender, or other identities, pervade how we perceive, think about, and act toward others. Research on the neural basis of prejudice seeks to illuminate its effects by investigating the neurocognitive processes through which prejudice is formed, represented in the mind, expressed in behavior, and potentially reduced. In this article, we review current knowledge about the social neuroscience of prejudice regarding its influence on rapid social perception, representation in memory, emotional expression and relation to empathy, and regulation, and we discuss implications of this work for prejudice reduction interventions.

Event-related brain potential correlates of the other-race effect: A review

People are better at remembering own-race relative to other-race faces. Here, we review event-related brain potential (ERP) correlates of this so-called other-'race' effect (ORE) by discussing three critical aspects that characterize the neural signature of this phenomenon. First, difficulties with other-race faces initially emerge during perceptual processing, which is indexed by an increased N170. Second, as evidenced by 'difference due to subsequent memory' effects, more effortful processing of other-race faces is needed for successful encoding into long-term memory. Third, ERP old/new effects reveal that a stronger engagement of processing resources is also required for successful retrieval of other-race faces from memory. The ERP evidence available to date thus suggests widespread ethnicity-related modulations during both perceptual and mnemonic processing stages. We further discuss how findings from the ORE compared with potentially related memory biases (e.g. other-gender or other-age effects) and how ERP findings inform the ongoing debate regarding the mechanisms underlying the ORE. Finally, we outline open questions and potential future directions with an emphasis on using multiple, ecologically more valid 'ambient' images for each face to assess the ORE in paradigms that capture identity rather than image recognition.

Doctors inhibit social threat empathy in the later stage of cognitive processing: Electrophysiological evidence

Previous studies have found that repeatedly exposed to a threatening situation may reduce doctors' level of empathy, reducing psychological stress and avoiding burnout and compassion fatigue. However, many essential studies found that it does not seem universal but rather modulated by group membership. In this study, we recorded event-related potentials (ERP) when doctors and controls watched visual stimuli describing patients attacking doctors (Threat events) or shaking hands with doctors (Neutral events). The present study showed an early N190 and a later centro-parietal P3 differential amplitude between threat stimuli and neutral stimuli were observed in the controls. For the doctors, there was such ERP differentiation in early N190. However, later stage P3 differential amplitude was not observed. The current research suggests that doctors could regulate empathy and avoid allocating more attention resources when processing social threats to ensure treatment efficiency and avoid burnout.

The Social Neuroscience of Prejudice

The social neuroscience approach to prejudice investigates the psychology of intergroup bias by integrating models and methods of neuroscience with the social psychology of prejudice, stereotyping, and discrimination. Here, we review major contemporary lines of inquiry, including current accounts of group-based categorization; formation and updating of prejudice and stereotypes; effects of prejudice on perception, emotion, and decision making; and the self-regulation of prejudice. In each section, we discuss key social neuroscience findings, consider interpretational challenges and connections with the behavioral literature, and highlight how they advance psychological theories of prejudice. We conclude by discussing the next-generation questions that will continue to guide the social neuroscience approach toward addressing major societal issues of prejudice and discrimination.

Effects of Minimal Grouping On Implicit Prejudice, Infrahumanization, and Neural Processing Despite Orthogonal Social Categorizations

Racial prejudice is a pervasive and pernicious form of intergroup bias. However, a mounting number of studies show that re-categorization-even into minimal groups-can overcome the typical consequences of racial and other group classifications. We tested the effects of minimal grouping on implicit prejudice and infrahumanization using a paradigm in which race was orthogonal to group membership. This allowed us to examine whether knowledge of group membership overrides obvious category differences. We found that participants infrahumanized and showed implicit bias toward the minimal out-group, despite the crosscutting presence of race, and in fact did not show any of the usual implicit racial bias. In addition, Event-Related Potentials (ERPs) showed an early race effect followed by distinct reactions on the basis of group as processing continued. This is evidence that arbitrary social classifications can engender in-group preference even in the presence of orthogonal, visually salient categorizations.

Learning own- and other-race facial identities: Testing implicit recognition with event-related brain potentials

Exposure to varying images of the same person can encourage the formation of a representation that is sufficiently robust to allow recognition of previously unseen images of this person. While behavioural work suggests that face identity learning is harder for other-race faces, the present experiment investigated the neural correlates underlying own- and other-race face learning. Participants sorted own- and other-race identities into separate identity clusters and were further familiarised with these identities in a matching task. Subsequently, we compared event-related brain potentials (ERPs) in an implicit recognition (butterfly detection) task for learnt and previously unseen identities. We observed better sorting and matching for own- than other-race identities, and behavioural learning effects were restricted to own-race identities. Similarly, the N170 ERP component showed clear learning effects for own-race faces only. The N250, a component more closely associated with face learning was more negative for learnt than novel identities. ERP findings thus suggests a processing advantage for own-race identities at an early perceptual level whereas later correlates of identity learning were unaffected by ethnicity. These results suggest learning advantages for own-race identities, which underscores the importance of perceptual expertise in the own-race bias.

Attention and Working Memory Biases to Black and Asian Faces During Intergroup Contexts

Categorizing and individual as a racial ingroup or outgroup member results in processing and memory differences. However, despite processing differences for racial ingroups and outgroups, very little is known about processing of racial ingroup and outgroup members during intergroup contexts. Thus, the present research investigated attention and memory differences for racial ingroup and outgroup members during competition for attention (i.e., intergroup contexts). In experiment 1, event-related potentials (ERPs) were obtained while participants completed a working memory task that presented 4 faces (2 Black, 2 White) at once then, following a short delay, were probed to indicate the spatial location of one of the faces. Participants showed better location memory for Black than White faces. During encoding, ERP results revealed differences based on the race of the face in P300 amplitudes, such that there was greater motivated processing when attending to Black faces. At probe, the N170 indicated enhanced early processing of Black faces and greater LPCs were associated with better recollection of Black face location. In a follow-up study using the same task, we examined attention and working memory biases for Asian and White faces in Caucasian and Asian participants. Results for both Caucasian and Asian participants indicated better working memory for Asian relative to White faces. Together, results indicate that during intergroup contexts, racial minority faces capture attention, resulting in better memory for those faces. The study underscores that examining racial biases with single stimuli paradigms obscures important aspects of attention and memory biases during intergroup contexts.

Social Categories Alone Are Insufficient to Elicit an In-Group Advantage in Perceptions of Within-Person Variability

Within-person variability affects identity perception of other-race faces more than own-race faces; when participants sort images into piles representing different identities, they sort photographs of two other-race identities into more piles than two own-race identities. These results have been interpreted in terms of perceptual expertise, such that lack of experience with other-race faces leads to reduced ability to extract identity-relevant information across images. However, an alternative explanation is that sociocognitive factors (e.g., cognitive disregard for out-group faces) lead to differences in the number of perceived identities. Here, we examined whether social factors alone elicit an in-group advantage in perceptions of within-person variability. Caucasian participants sorted 40 photographs of two unfamiliar Caucasian identities (20 photographs/model) into piles based on the number of identities they believed were present. Half of the participants were told that the images were of students attending their university (in-group), whereas half were told that the images were of students attending a rival university (out-group). Participants sorted the photographs into a comparable number of identities for in- and out-group faces. This lack of an in-group advantage suggests that sociocognitive factors alone cannot account for differences in the number of perceived identities across faces from two categories.

Power effects on implicit prejudice and stereotyping: The role of intergroup face processing

Power is thought to increase discrimination toward subordinate groups, yet its effect on different forms of implicit bias remains unclear. We tested whether power enhances implicit racial stereotyping, in addition to implicit prejudice (i.e., evaluative associations), and examined the effect of power on the automatic processing of faces during implicit tasks. Study 1 showed that manipulated high power increased both forms of implicit bias, relative to low power. Using a neural index of visual face processing (the N170 component of the ERP), Study 2 revealed that power affected the encoding of White ingroup vs. Black outgroup faces. Whereas high power increased the relative processing of outgroup faces during evaluative judgments in the prejudice task, it decreased the relative processing of outgroup faces during stereotype trait judgments. An indirect effect of power on implicit prejudice through enhanced processing of outgroup versus ingroup faces suggested a potential link between face processing and implicit bias. Together, these findings demonstrate that power can affect implicit prejudice and stereotyping as well as early processing of racial ingroup and outgroup faces.