Opposite aftereffects for Chinese and Caucasian faces are selective for social category information and not just physical face differences

Opposite changes in perception (aftereffects) can be simultaneously induced for faces from different social categories—for example, Chinese and Caucasian faces. We investigated whether these aftereffects are generated in high-level face coding that is sensitive to the social category information in faces, or in earlier visual coding sensitive to simple physical differences between faces. We caricatured the race of face stimuli and created face continua ranging from caricatured Caucasian faces (SuperCaucasian) to caricatured Chinese faces (SuperChinese). Participants were adapted to oppositely distorted faces that were a fixed physical distance apart on the morph continua. Larger opposite aftereffects were found following adaptation to faces from different race categories (e.g., contracted Chinese and expanded Caucasian faces), than for faces that were the same physical distance apart on the morph continua, but were within a race category (e.g., contracted SuperChinese and expanded Chinese faces). These results suggest that opposite aftereffects for Chinese and Caucasian faces reflect the recalibration of face neurons tuned to high-level social category information.     

Sex-contingent face aftereffects depend on perceptual category rather than structural encoding

Many studies have used visual adaptation to investigate how recent experience with faces influences perception. While faces similar to those seen during adaptation phases are typically perceived as more 'normal' after adaptation, it is possible to induce aftereffects in one direction for one category (e.g. female) and simultaneously induce aftereffects in the opposite direction for another category (e.g. male). Such aftereffects could reflect 'category-contingent' adaptation of neurons selective for perceptual category (e.g. male or female) or 'structure-contingent' adaptation of lower-level neurons coding the physical characteristics of different face patterns. We compared these explanations by testing for simultaneous opposite after effects following adaptation to (a) two groups of faces from distinct sex categories (male and female) or (b) two groups of faces from the same sex category (female and hyper-female) where the structural differences between the female and hyper-female groups were mathematically identical to those between male and female groups. We were able to induce opposite aftereffects following adaptation between sex categories but not after adaptation within a sex category. These findings indicate the involvement of neurons coding perceptual category in sex-contingent face aftereffects and cannot be explained by neurons coding only the physical aspects of face patterns.     

Race-contingent aftereffects suggest distinct perceptual norms for different race faces

Faces of one's own race and of other races are thought to be located in different regions of face space (Valentine, 1991 Valentine, T. 1991. A unified account of the effects of distinctiveness, inversion, and race in face recognition. Quarterly Journal of Experimental Psychology, 43A: 161–204. [Taylor & Francis Online] , [Google Scholar]). Here we investigated whether faces of different races (Caucasian and Chinese faces) have dissociable neural coding and distinct norms. We used adaptation techniques to alter perceptions of normality (aftereffects) for faces. Caucasian and Chinese participants adapted to distorted faces of one race (e.g., Chinese contracted faces—Experiment 1), or oppositely distorted faces of both races (e.g., Chinese contracted and Caucasian expanded faces—Experiment 2). We then tested for aftereffects in Chinese and Caucasian test faces. In Experiment 1 aftereffects were reduced when a change in race between the adapt faces and test faces occurred. In Experiment 2 aftereffects occurred in opposite directions for the two races. These results demonstrate that dissociable neural populations code faces of different races and suggest the existence of race-specific face norms.     

Face aftereffects indicate dissociable, but not distinct, coding of male and female faces

It has been claimed that exposure to distorted faces of one sex induces perceptual aftereffects for test faces that are of the same sex, but not for test faces of the other sex (A. C. Little, L. M. DeBruine, & B. C. Jones, 2005). This result suggests that male and female faces have separate neural coding. Given the high degree of visual similarity between faces of different sexes, this result is surprising. The authors reinvestigated male and female face coding using a different face distortion. In Experiment 1, participants adapted to distorted faces from one sex (e.g., male contracted faces) and were tested with faces of both sexes. Aftereffects were found for both male and female faces, suggesting the existence of common coding mechanisms. In Experiments 2 and 3, participants adapted to oppositely distorted faces from both sexes (male contracted and female expanded faces). Weak opposite aftereffects were found for male and female faces, suggesting the existence of sex-selective face coding mechanisms. Taken together, these results indicate that both common and sex-selective mechanisms code male and female faces.     

The development of norm-based coding and race-specific face prototypes: An examination of 5- and 8-year-olds’ face space

The current research investigated the organization of children’s face space by examining whether 5- and 8-year-olds show race-contingent aftereffects. Participants read a storybook in which Caucasian and Chinese children’s faces were distorted in opposite directions. Before and after adaptation, participants judged the normality/attractiveness of expanded, compressed, and undistorted Caucasian and Chinese faces. The method was validated with adults and then refined to test 8- and 5-year-olds. The 5-year-olds were also tested in a simple aftereffects paradigm. The current research provides the first evidence for simple attractiveness aftereffects in 5-year-olds and for race-contingent aftereffects in both 5- and 8-year-olds. Evidence that adults and 5-year-olds may possess only a weak prototype for Chinese children’s faces suggests that Caucasian adults’ prototype for Chinese adult faces does not generalize to child faces and that children’s face space undergoes a period of increasing differentiation between 5 and 8 years of age.     

Representing young and older adult faces: Shared or age-specific prototypes?

ABSTRACT

Young adults recognize young adult faces more accurately than older adult faces and are more sensitive to how individual young faces deviate from a norm/prototype. Here we used an adaptation paradigm to examine whether young and older adult faces are represented by separable norms and the extent to which the coding dimensions for these two categories overlap. In Experiment 1, following adaptation to oppositely distorted young and older faces (e.g., expanded young and compressed older faces), adults’ normality judgments simultaneously shifted in opposite directions for the two face categories, providing evidence for separable norms. In Experiment 2, participants were adapted to distorted faces from a single age category (e.g., compressed young); aftereffects transferred across face age but were larger for the face age that matched adaptation. Collectively, these results provide evidence that young and older faces are processed with regard to separable norms that share some underlying coding dimensions.     

Categorization,categorical perception,and asymmetry in infants’ representation of face race

The present study examined whether 6‐ and 9‐month‐old Caucasian infants could categorize faces according to race. In Experiment 1, infants were familiarized with different female faces from a common ethnic background (i.e. either Caucasian or Asian) and then tested with female faces from a novel race category. Nine‐month‐olds were able to form discrete categories of Caucasian and Asian faces. However, 6‐month‐olds did not form discrete categories of faces based on race. In Experiment 2, a second group of 6‐ and 9‐month‐olds was tested to determine whether they could discriminate between different faces from the same race category. Results showed that both age groups could only discriminate between different faces from the own‐race category of Caucasian faces. The findings of the two experiments taken together suggest that 9‐month‐olds formed a category of Caucasian faces that are further differentiated at the individual level. In contrast, although they could form a category of Asian faces, they could not discriminate between such other‐race faces. This asymmetry in category formation at 9 months (i.e. categorization of own‐race faces vs. categorical perception of other‐race faces) suggests that differential experience with own‐ and other‐race faces plays an important role in infants’ acquisition of face processing abilities.     

Face aftereffects suggest interdependent processing of expression and sex and of expression and race

Bruce and Young (1986) proposed that functionally different aspects of faces (e.g., sex, identity, and expression) are processed independently. Although interdependent processing of identity and expression and of identity and sex have been demonstrated previously, evidence for interdependent processing of sex and expression is equivocal. Using a visual adaptation paradigm, we show that expression aftereffects can be simultaneously induced in different directions along anger–fear continua for male and female faces (Experiment 1) and for East Asian and Black African faces (Experiment 2). These findings for sex- and race-contingent expression aftereffects suggest that processing of expression is interdependent with processing of sex and race and are therefore problematic for models of face perception that have emphasized independent processing of functionally different aspects of faces. By contrast, our findings are consistent with models of face processing that propose that invariant physical aspects of faces and changeable social cues can be processed interdependently.     

Category-contingent face adaptation for novel colour categories: Contingent effects are seen only after social or meaningful labelling

A face appears normal when it approximates the average of a population. Consequently, exposure to faces biases perceptions of subsequently viewed faces such that faces similar to those recently seen are perceived as more normal. Simultaneously inducing such aftereffects in opposite directions for two groups of faces indicates somewhat discrete representations for those groups. Here we examine how labelling influences the perception of category in faces differing in colour. We show category-contingent aftereffects following exposure to faces differing in eye spacing (wide versus narrow) for blue versus red faces when such groups are consistently labelled with socially meaningful labels (Extravert versus Introvert; Soldier versus Builder). Category-contingent aftereffects were not seen using identical methodology when labels were not meaningful or were absent. These data suggest that human representations of faces can be rapidly tuned to code for meaningful social categories and that such tuning requires both a label and an associated visual difference. Results highlight the flexibility of the cognitive visual system to discriminate categories even in adulthood.     

View-specific coding of face shape

Monkey and human cortex contain view-specific face neurons, but it remains unclear whether they code face shape. We tested the view specificity of face-shape coding by inducing figural face aftereffects at one viewpoint (3/4 left) and testing generalization to different viewpoints (front view and 3/4 right). The aftereffects were induced by adaptation to consistent figural distortions (contracted or expanded), which shifts the distortion perceived as most normal toward the adapting distortion. The strong aftereffect that was observed at the adapting view was significantly and substantially reduced for both front-view test faces and mirror-image (3/4 right) test faces, indicating view specificity. The limited transfer across mirror views is strong evidence of view specificity, given their figural similarity. The aftereffects survived a size change between adaptation and test faces (Experiment 2), a result that rules out low-level adaptation as an explanation. These results provide strong evidence that face-shape coding is view-specific.     

Category contingent aftereffects for faces of different races, ages and species

Exposure to faces biases perceptions of subsequently viewed faces such that normality judgments of similar faces are increased. Simultaneously inducing such an aftereffect in opposite directions for two groups of faces might indicate discrete responding of the neural populations coding for those groups. Here we show such "category contingent" aftereffects following exposure to faces differing in eye-spacing (wide versus narrow) for European versus African faces, adult versus infant faces, and human versus monkey faces. As aftereffects reflect changes in responses of neural populations that code faces, our results may then suggest that functionally distinct neural populations code faces of different ages, races and species and that the human brain potentially contains discrete representations of these categories.     

Contact,configural coding and the other‐race effect in face recognition

The other‐race effect (ORE) in face recognition describes a well‐established finding of better recognition for own‐race than other‐race faces. Although widely thought to reflect differences in contact between own‐ and other‐race faces, little is known about how different contact levels relate to changes in processing of those faces. This study investigated how contact affects the size of the ORE and the use of expert configural face‐coding mechanisms. Using inversion decrements as an index of configural coding, we predicted that increased self‐reported contact would be associated with greater use of configural‐coding mechanisms. Chinese and Caucasian participants varying in contact with other‐race faces were recruited. The Chinese participants also varied in their length of residence in a Western country. Results showed that higher levels of contact were associated with a reduction in the ORE in both face recognition and configural coding. Importantly, smaller cross‐race differences in configural coding were also associated with a smaller ORE in face recognition.     

知觉适应对种族融合面孔的种族分类和知觉辨别的影响

面孔加工的种族效应(the other-race effects)指人们对面孔做个体辨别任务时辨别本族面孔的绩效优于辨别他族面孔的绩效, 而做种族分类任务时分类他族面孔的绩效优于分类本族面孔的绩效。本研究通过知觉适应操纵被试对种族两歧(高加索和亚洲)融合面孔的种族知觉, 进而比较被试在两种条件下对同一张融合面孔进行种族分类和知觉辨别的绩效的差异。结果发现, 知觉适应能使被试产生将两歧融合面孔知觉为与原始面孔所属种族相反种族的知觉偏向, 并且, 伴随着这种知觉偏向, 两歧融合面孔的加工出现了他族分类优势和本族辨别优势, 提示社会认知因素对面孔加工的种族效应有重要作用。     

An encoding advantage for own-race versus other-race faces

Studies have shown that individuals are better able to recognise the faces of people from their own race than the faces of people from other races. Although the so-called own-race effect has been generally regarded as an advantage in recognition memory, differences in the processing of the own-race versus other-race faces might also be found at the earlier stages of perceptual encoding. In this study, the perceptual basis of the own-race effect was investigated by generating a continuum of images by morphing an East Asian parent face with a Caucasian parent face. In a same/different discrimination task, East Asian and Caucasian participants judged whether the morph faces were physically identical to, or different from, their parent faces. The results revealed a significant race-of-participant by race-of-face interaction such that East Asian participants were better able to discriminate East Asian faces, whereas Caucasian participants were better able to discriminate Caucasian faces. These results indicate that an own-race advantage occurs at the encoding stage of face processing.     

Infant preference for female faces occurs for same‐ but not other‐race faces

There has been a recent surge of interest in the question of how infants respond to the social attributes of race and gender information in faces. This work has demonstrated that by 3 months of age, infants will respond preferentially to same‐race faces and faces depicting the gender of the primary caregiver. In the current study, we investigated emergence of the female face preference for same‐ versus other‐race faces to examine whether the determinants of preference for face gender and race are independent or interactive in young infants. In Expt 1, 3‐month‐old Caucasian infants displayed a preference for female over male faces when the faces were Caucasian, but not when the faces were Asian. In Expt 2, new‐born Caucasian infants did not demonstrate a preference for female over male faces for Caucasian faces. The results are discussed in terms of a face prototype that becomes progressively tuned as it is structured by the interaction of the gender and race of faces that are experienced during early development.     

Atypical updating of face representations with experience in children with autism

Face identity aftereffects are significantly diminished in children with autism relative to typical children, which may reflect reduced perceptual updating with experience. Here, we investigated whether this atypicality also extends to non‐face stimulus categories, which might signal a pervasive visual processing difference in individuals with autism. We used a figural aftereffect task to measure directly perceptual updating following exposure to distorted upright faces, inverted faces and cars, in typical children and children with autism. A size‐change between study and test stimuli limited the likelihood that any processing atypicalities reflected group differences in adaptation to low‐level features of the stimuli. Results indicated that, relative to typical children, figural aftereffects for upright faces, but not inverted faces or cars, were significantly attenuated in children with autism. Moreover, the group difference was amplified when we isolated the ‘face‐selective’ component of the aftereffect, by partialling out the mid‐level shape adaptation common to upright and inverted face stimuli. Notably, the aftereffects of typical children were disproportionately larger for upright faces than for inverted faces and cars, but the magnitude of aftereffects of autistic children was not similarly modulated according to stimulus category. These findings are inconsistent with a pervasive adaptive coding atypicality relative to typical children, and suggest that reduced perceptual updating may constitute a high‐level, and possibly face‐selective, visual processing difference in children with autism.     

Attending but not seeing: The "other race" effect in face and person perception studied through change blindness

We used a change blindness paradigm to examine the “other race” effect in perception. White Caucasian and Indian Asian participants viewed scenes in which White Caucasian and Indian Asian students were present. Changes were made either to the faces of the students, to their bodies or to an independent object in the background. Changes in faces were detected faster than changes in the bodies, which were in turn detected faster than changes in the background. For face detection there was a crossover interaction, with changes in White Caucasian faces detected faster than changes in Indian Asian faces by White Caucasian participants, whilst the opposite result occurred for changes in Indian Asian faces. In contrast, there was no effect of race on the detection of body-part changes or on the detection of changes to background objects. The results suggest that participants of both races attended equally well to subjects from the other race in the scene, but despite this they remained less sensitive to “other race” faces. Change blindness can provide a useful way of analysing attentional and memorial processes in social contexts.     

Identification of own-race and other-race faces: Implications for the representation of race in face space

Own-race faces are recognized more easily than faces of a different, unfamiliar race. According to the multidimensional space (MDS) framework, the poor discriminability of other-race faces is due to their being more densely clustered in face space than own-race faces. Multidimensional scaling analyses of similarity ratings (Caucasian participants, n = 22) showed that other-race (Chinese) faces are more densely clustered in face space. We applied a formal model to test whether the spatial location of face stimuli could account for identification accuracy of another group of Caucasian participants (n = 30). As expected, own-race (Caucasian) faces were identified more accurately (higher hit rate, lower false alarms, and higher A) than other-race faces, which were more densely clustered than ownrace faces. A quantitative model successfully predicted identification performance from the spatial locations of the stimuli. The results are discussed in relation to the standard MDS account of race effects and also an alternative “race-feature” hypothesis.     

Face recognition as a predictor of social cognitive ability: Effects of emotion and race on face processing

The human face conveys important social signals when people interact in social contexts. The current study investigated the relationship between face recognition and emotional intelligence, and how societal factors of emotion and race influence people's face recognition. Participants’ recognition accuracy, reaction time, sensitivity, and response bias were measured to examine their face‐processing ability. Fifty Caucasian undergraduates (38 females, 12 males; average age = 21.76 years) participated in a face recognition task in which they discriminated previously presented target faces from novel distractor faces. A positive correlation between participants’ emotional intelligence scores and their performance on the face recognition task was observed, suggesting that face recognition ability was associated with emotional or social intelligence. Additionally, Caucasian participants recognized happy faces better than angry or neutral faces. It was also observed that people recognized Asian faces better than Caucasian ones, which appears to be contradictory to the classic other‐race effect. The present study suggests that some societal factors could influence face processing, and face recognition ability could in turn predict social intelligence.     

When memory shifts toward more typical category exemplars: accentuation effects in the recollection of ethnically ambiguous faces

In 4 studies, the authors examined the impact of categorization on the recollection of ethnically ambiguous faces. Participants were presented with faces lying at various locations on mixed-race continua (i.e., Caucasian-North African and Caucasian-Asian faces were used as source images in a morphing program). In all studies, the prevalence of exclusive ethnic features in a face distorted participants' recollections of the face toward faces more typical of the category. Specifically, the recollection of 30% North African (or 30% Asian) faces shifted toward Caucasian source faces, whereas the recollection of 70% North African (or 70% Asian) faces shifted toward North African (Asian) source faces. Memory distortions did not emerge for extremely ambiguous (50%) faces and proved larger on mixed-race than same-race continua (Studies 3 and 4). Memory distortions also emerged with high levels of confidence. The authors elaborate on the theoretical and practical implications of these findings.