Inequality between biases in face memory: Event-related potentials reveal dissociable neural correlates of own-race and own-gender biases

Face motion form at learning influences the time course of face spatial frequency processing during test

Studies that use static faces suggest that facial processing follows a coarse-to-fine sequence; i.e., holistic precedes featural processing, due to low and high spatial frequencies (LSF, HSF) transmitting holistic/global and featural/local information respectively. Although recent studies have focused on the role of facial movement in holistic facial processing, it is unclear whether moving faces have the same processing mechanism as static ones, especially in the time course of processing. The current study uses the event-related potential technique to investigate this issue by manipulating the facial format at study and face spatial frequency during the test. ERP results showed that the P1 amplitude was increased by LSF faces relative to HSF ones, using both moving and static study faces, with the former larger than the latter. The N170 amplitude was more sensitive to HSF than LSF faces when only static study faces were used, while the P2 amplitude was more sensitive to LSF faces regardless of the facial study format. The above results were not modulated by the race of the faces. These results favor the view that regardless of face race, moving study faces promote holistic processing during the earliest stage of face recognition. Furthermore, holistic processing is observed to be the same for both static and moving study faces at a later stage associated with more in-depth processing. It is evident that facial motion should be factored into further studies of face recognition, given the distinctions between holistic and featural processing for moving and static study faces.

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.

Default categorization of outgroup faces and the other race effect: Commentary on the special issue

This commentary addresses how studies examining the neurophysiological correlates of racial categorization can provide insight into the neurocognitive mechanisms of the other-race effect in recognition memory. Several articles in the special issue describe how event-related potentials (ERPs) have been used to examine processing of faces that vary according to race, some of which have concluded that larger ERP amplitudes elicited by other-race (relative to own-race) faces indicates less efficient visual processing of other-race faces. I describe findings from ERP studies of race categorization that suggest an alternative interpretation-that other-race faces elicit stronger categorization, which impedes individuation of other-race faces. Suggestions for future research are offered.

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.

Understanding racial bias through electroencephalography

Research on racial bias in social and cognitive psychology has focused on automatic cognitive processes such as categorisation or stereotyping. Neuroimaging has revealed differences in the neural circuit when processing social information about one's own or another's ethnicity. This review investigates the influence of racial bias on human behaviour by reviewing studies that examined changes in neural circuitry (i.e. ERP responses) during automatic and controlled processes elicited by specific tasks. This systematic analysis of specific ERP components across different studies provides a greater understanding of how social contexts are perceived and become associated with specific stereotypes and behavioural predictions. Therefore, investigating these related cognitive and neurobiological functions can further our understanding of how racial bias affects our cognition more generally and guide more effective programs and policies aimed at its mitigation.

Real-life outgroup exposure, self-reported outgroup contact and the other-race effect

People are better at recognizing faces from their own racial or ethnic group compared with faces from other racial or ethnic groups, known as the other-'race' effect (ORE). Several theories of the ORE assume that memory for other-race faces is impaired because people have less contact with members of other racial or ethnic groups, resulting in lower visual expertise. The present research investigates contact theories of the ORE, using self-report contact measures and objective measures of potential outgroup exposure (estimated from participants' residential location and from GPS tracking). Across six studies (total N = 2660), we observed that White American and White German participants displayed better memory for White faces compared with Black or Middle Eastern faces, whereas Black American participants displayed similarly equal or better memory for White compared with Black faces. We did not observe any relations between the ORE and objective measures of potential outgroup exposure. Only in Studies 2a and 2b, we observed very small correlations (rs = -.08 to .06) between 4 out of 30 contact measures and the ORE. We discuss methodological limitations and implications for theories of the ORE.

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.

Race and early face-sensitive event-related potentials in children and adults

Studies examining children's face perception have revealed developmental changes in early and face-sensitive event-related potential (ERP) components. Children also tend to show racial biases in their face perception and evaluation of others. The current study examined how early face-sensitive ERPs are influenced by face race in children and adults. A second objective examined face recognition proficiency and implicit racial bias in relation to ERP responses to own- and other-race faces. Electroencephalographic responses were recorded while Caucasian children and adults viewed Caucasian and East Asian faces. Participants also completed recognition tasks and an IAT with Caucasian and East Asian faces. Other-race faces elicited larger P100 amplitudes than own-race faces. Furthermore, adults with better other-race recognition proficiency showed larger P100 amplitude responses to other-race faces compared with adults with worse other-race recognition proficiency. In addition, larger implicit biases favoring own-race individuals were associated with larger P100 to N170 peak-to-peak amplitudes for other-race faces in adults. In contrast, larger implicit biases favoring own-race individuals were associated with smaller P100 to N170 peak-to-peak amplitudes for both own- and other-race faces in 8- to 10-year-olds. There was also an age-related decrease in P100 to N170 peak-to-peak amplitudes for own-race faces among 5- to 10-year-olds with better own-race recognition proficiency. The age-related decrease in N170 latency for other-race faces was also more pronounced in 5- to 10-year-olds with better other-race recognition proficiency. Thus, recognition proficiency and implicit racial bias are associated with early ERP responses in adults and children, but in different ways.

Do perceptual expertise and implicit racial bias predict early face-sensitive ERP responses?

Studies examining the visual perception of face race have revealed mixed findings regarding the presence or direction of effects on early face-sensitive event-related potential (ERP) components. Few studies have examined how early ERP components are influenced by individual differences in bottom-up and top-down processes involved in face perception, and how such factors might interact to influence early face-sensitive ERP components has yet to be investigated. Thus, the current study examined whether P100, N170, and P200 responses can be predicted by individual differences in own- and other-race face recognition, implicit racial bias, and their interaction. Race effects were observed in the P100, N170, and P200 responses. Other-race face recognition, implicit racial biases, and their interaction explained a significant amount of unique variability in N170 responses when viewing other-race faces. Responses to own-race faces were minimally influenced with only implicit racial bias predicting a significant amount of unique variability in N170 latency when viewing own-race faces. Face recognition, implicit racial bias, or their interaction did not predict P100 responses. The current findings suggest that face recognition abilities and its interaction with implicit racial bias modulate the early stages of other-race face processing.

Recognising other-race faces is more effortful: The effect of individuation instructions on encoding-related ERP Dm effects

Humans are better at recognising faces from their own vs. another ethnic background. Socio-cognitive theories of this own-race bias (ORB) propose that reduced recognition of other-race faces results from less motivation to attend to individuating information during encoding. Accordingly, individuation instructions that explain the phenomenon and instruct participants to attend to other-race faces during learning attenuate or eliminate the ORB. However, it is still unclear how exactly such instructions affect other-race face processing. We addressed this question by investigating encoding-related event-related brain potentials, contrasting neural activity of subsequently remembered and forgotten items (Dm effects). In line with socio-cognitive accounts, individuation instructions reduced the ORB. Critically, instructions increased Dm effects for other-race faces, suggesting that more processing resources were allocated to these faces during encoding. Thus, compensating for reduced experience with other-race faces is possible to some extent, but additional resources are needed to decrease difficulties resulting from a lack of perceptual expertise.

Spouses' faces are similar but do not become more similar with time

The widely disseminated convergence in physical appearance hypothesis posits that long-term partners’ facial appearance converges with time due to their shared environment, emotional mimicry, and synchronized activities. Although plausible, this hypothesis is incompatible with empirical findings pertaining to a wide range of other traits—such as personality, intelligence, attitudes, values, and well-being—in which partners show initial similarity but do not converge over time. We solve this conundrum by reexamining this hypothesis using the facial images of 517 couples taken at the beginning of their marriages and 20 to 69 years later. Using two independent methods of estimating their facial similarity (human judgment and a facial recognition algorithm), we show that while spouses’ faces tend to be similar at the beginning of marriage, they do not converge over time, bringing facial appearance in line with other personal characteristics.

Evaluating the independence of age, sex, and race in judgment of faces

Extracting the dimensions of age, sex, race from faces is fundamental for many aspects of social cognition such as person construal, impression formation, and social interaction. While cognitive researchers consider these dimensions to be independent in processing, social psychology researchers have recently demonstrated the emergence of strong interactive patterns between these categories, especially, when social biases are involved. The current study harnessed the classic Garner's speeded classification task (Garner, 1974) and Stroop task (1935) to evaluate the level of independence between age, sex, and race in a systematic and exhaustive fashion, with an eye on the potential influence of social biases. The degree of separability was evaluated in a pairwise fashion, with each experiment testing one pair. In Experiment 1a and 1b, sex and race were tested with strong (Experiment 1b) or weak (Experiment 1a) social bias. Experiment 2 was set to assess the separability of sex and race. And Experiment 3 was aimed at evaluating the separability of age and sex. The results revealed that neither of the pairs of dimensions produced Garner interferences (and are therefore separable dimensions). However, when strong social bias was present, the dimensions did produce redundancy gains and Stroop-like effects, which reflected the presence of abiding social biases. A holistic-to-analytic model is presented to account for these results, according to which, the dimensions are initially processed as integral dimensions, but then become gradually separable.

Gender Differences in Familiar Face Recognition and the Influence of Sociocultural Gender Inequality

Are gender differences in face recognition influenced by familiarity and socio-cultural factors? Previous studies have reported gender differences in processing unfamiliar faces, consistently finding a female advantage and a female own-gender bias. However, researchers have recently highlighted that unfamiliar faces are processed less efficiently than familiar faces, which have more robust, invariant representations. To-date, no study has examined whether gender differences exist for familiar face recognition. The current study addressed this by using a famous faces task in a large, web-based sample of  > 2000 participants across different countries. We also sought to examine if differences varied by socio-cultural gender equality within countries. When examining raw accuracy as well when controlling for fame, the results demonstrated that there were no participant gender differences in overall famous face accuracy, in contrast to studies of unfamiliar faces. There was also a consistent own-gender bias in male but not female participants. In countries with low gender equality, including the USA, females showed significantly better recognition of famous female faces compared to male participants, whereas this difference was abolished in high gender equality countries. Together, this suggests that gender differences in recognizing unfamiliar faces can be attenuated when there is enough face learning and that sociocultural gender equality can drive gender differences in familiar face recognition.

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.

The effect of educational priming on face recognition from a silver alert

In a between-subjects' experimental design, we manipulated whether participants viewed an educational video on the importance of Silver Alerts before viewing an older Caucasian female in a Silver Alert. We also examined associations of target recognition with individual difference variables, including gender, ethnicity, Attitudes Towards Older People (ATOP), empathy, conscientiousness, as well as contact and experience with older adults. The results showed an advantage of the priming condition compared to the no-priming condition for correctly identifying the missing woman. Additionally, females correctly identified the missing woman more than males, and Caucasian participants correctly identified the missing woman more than African American participants. Lastly, participants who reported more experience with older adults were more likely to recognize the missing woman. The results suggest that preceding Silver Alerts with information about their importance may increase their effectiveness. Further research is needed to investigate how individual difference variables relate to recognition of missing senior citizens.

Learning own- and other-race facial identities from natural variability

Exposure to multiple varying face images of the same person encourages the formation of identity representations which are sufficiently robust to allow subsequent recognition from new, never-before seen images. While recent studies suggest that identity information is initially harder to perceive in images of other- relative to own-race identities, it remains unclear whether these difficulties propagate to face learning, that is, to the formation of robust face representations. We report two experiments in which Caucasian and East Asian participants sorted multiple images of own- and other-race persons according to identity in an implicit learning task and subsequently either matched novel images of learnt and previously unseen faces for identity (Experiment 1) or made old/new decisions for new images of learnt and unfamiliar identities (Experiment 2). Caucasian participants demonstrated own-race advantages during sorting, matching, and old/new recognition, while corresponding effects were absent in East Asian participants with substantial other-race expertise. Surprisingly, East Asian participants showed enhanced learning for other-race identities during matching in Experiment 1, which may reflect their increased motivation to individuate other-race faces. Thus, our results highlight the importance of perceptual expertise for own- and other-race processing, but may also lend support to recent suggestions on how expertise and socio-cognitive factors can interact.

Intentionally remembering or forgetting own- and other-race faces: Evidence from directed forgetting

People are better at remembering faces of their own relative to another ethnic group. This so-called own-race bias (ORB) has been explained in terms of differential perceptual expertise for own- and other-race faces or, alternatively, as resulting from socio-cognitive factors. To test predictions derived from the latter account, we examined item-method directed forgetting (DF), a paradigm sensitive to an intentional modulation of memory, for faces belonging to different ethnic and social groups. In a series of five experiments, participants during learning received cues following each face to either remember or forget the item, but at test were required to recognize all items irrespective of instruction. In Experiments 1 and 5, Caucasian participants showed DF for own-race faces only while, in Experiment 2, East Asian participants with considerable expertise for Caucasian faces demonstrated DF for own- and other-race faces. Experiments 3 and 4 found clear DF for social in- and outgroup faces. These results suggest that a modulation of face memory by motivational processes is limited to faces with which we have acquired perceptual expertise. Thus, motivation alone is not sufficient to modulate memory for other-race faces and cannot fully explain the ORB.

The Own-Race Bias and the cerebral hemispheres

The Own-Race Bias (ORB) is the ability to better recognize and categorize a face when the depicted person belongs to the observer's ethnicity group. The relationship between the ORB and hemispheric asymmetries has been poorly explored, and the present study was aimed at investigating this relationship, as well as that between the ORB and the bias to better recognize own gender faces. Female and male Caucasian participants categorized the ethnicity of Caucasian and Asian female and male facial stimuli in a divided visual field paradigm. In a control experiment the same stimuli were presented centrally, confirming the ORB. Importantly, the lateralized presentation reversed the bias with higher accuracy and shorter response times in the categorization of Asian than Caucasian faces. This reversed bias was significant for female and male faces, and it was observed when stimuli were presented in the left but not in the right visual field, revealing the crucial role of the right hemisphere in face processing. These results shed new light on the hemispheric abilities in the categorization of facial features, and they are compared to previous evidence of cerebral asymmetries for facial age, gender and identity, both in healthy participants and in neurological patients.

Same-gender distractors are not so easy to reject: ERP evidence of gender categorization

Social categorization appears to be an automatic process that occurs during person perception. Understanding social categorization better is important because mere categorization can lead to stereotype activation and, in turn, to discrimination. In the present study we used a novel approach to examine event-related potentials (ERPs) of gender categorization in the “Who said what?” memory paradigm, thus allowing for a more in-depth understanding of the specific mechanisms underlying identity versus categorization processing. After observing video clips showing a “discussion” among female and male targets, participants were shown individual statements, each accompanied by one of the discussants’ faces. While we measured ERPs, participants had to decide whether or not a given statement had previously been made by the person with the accompanying face. In same-person trials, statements were paired with the correct person, whereas in the distractor trials, either a same-gender or a different-gender distractor was shown. As expected, participants were able to reject different-gender distractors faster than same-gender distractors, and they were more likely to falsely choose yes for a same-gender than for a different-gender distractor. Both findings indicate gender-based categorization. ERPs, analyzed in a 300- to 400-ms time window at occipito-temporal channels, indicated more negative amplitudes for yes responses both for the same person and for same-gender distractors, relative to different-gender distractors. Overall, these results show gender-based categorization even when the task was to assess the identifying information in a gender-neutral context. These findings are interpreted as showing that gender categorization occurs automatically during person perception, but later than race- or age-based categorization.