Narrowing in categorical responding to other-race face classes by infants

Infants can form object categories based on perceptual cues, but their ability to form categories based on differential experience is less clear. Here we examined whether infants filter through perceptual differences among faces from different other-race classes and represent them as a single other-race class different only from own-race faces. We used a familiarization/novelty-preference procedure to investigate category formation for two other-race face classes (Black vs. Asian) by White 6- and 9-month-olds. The data indicated that while White 6-month-olds categorically represented the distinction between Black and Asian faces, White 9-month-olds formed a broad other-race category inclusive of Black and Asian faces, but exclusive of own-race White faces. The findings provide evidence that narrowing can occur for mental processes other than discrimination: category formation is also affected. The results suggest that frequency of experience with own-race versus other-race classes of faces may propel infants to contrast own-race faces with other-race faces, but not different classes of other-race faces with each other.

Angry facial expressions bias gender categorization in children and adults: behavioral and computational evidence

Angry faces are perceived as more masculine by adults. However, the developmental course and underlying mechanism (bottom-up stimulus driven or top-down belief driven) associated with the angry-male bias remain unclear. Here we report that anger biases face gender categorization toward “male” responding in children as young as 5–6 years. The bias is observed for both own- and other-race faces, and is remarkably unchanged across development (into adulthood) as revealed by signal detection analyses (Experiments 1–2). The developmental course of the angry-male bias, along with its extension to other-race faces, combine to suggest that it is not rooted in extensive experience, e.g., observing males engaging in aggressive acts during the school years. Based on several computational simulations of gender categorization (Experiment 3), we further conclude that (1) the angry-male bias results, at least partially, from a strategy of attending to facial features or their second-order relations when categorizing face gender, and (2) any single choice of computational representation (e.g., Principal Component Analysis) is insufficient to assess resemblances between face categories, as different representations of the very same faces suggest different bases for the angry-male bias. Our findings are thus consistent with stimulus-and stereotyped-belief driven accounts of the angry-male bias. Taken together, the evidence suggests considerable stability in the interaction between some facial dimensions in social categorization that is present prior to the onset of formal schooling.

Development of visual preference for own- versus other-race faces in infancy

Previous research has shown that 3-month-olds prefer own- over other-race faces. The current study used eye-tracking methodology to examine how this visual preference develops with age beyond 3 months and how infants differentially scan between own- and other-race faces when presented simultaneously. We showed own- versus other-race face pairs to 3-, 6-, and 9-month-old Chinese infants. In contrast with 3-month-olds' visual preference for own-race faces, 9-month-olds preferentially looked more at other-race faces. Analyses of eye-tracking data revealed that Chinese infants processed own- and other-race faces differentially. These findings shed important light on the role of visual experience in the development of visual preference and its relation to perceptual narrowing.

Do individuals with autism spectrum disorder process own- and other-race faces differently?

Individuals with autism spectrum disorder (ASD) process human faces in atypical ways according to previous literature. We investigated whether individuals with ASD can process face race information and respond to own- and other-race faces differentially. Chinese individuals with ASD (n=24), typically developing (TD) individuals (n=28), and individuals with intellectual disabilities (ID, n=26) were asked to recognize Chinese and Caucasian faces in an old-new face paradigm using eye tracking. In terms of recognition, the ASD and ID groups did not perform differently and displayed superior own-race recognition compared with other-race faces; TD participants displayed similar recognition of the two types of faces. In terms of eye tracking, the TD, ASD, and ID groups displayed more looking on the eyes and less looking on the nose and mouth of Caucasian faces relative to Chinese faces. Overall, individuals with ASD manifested a behavioral other-race effect and displayed the same type of cross-racial differentiation in face scanning observed in TD individuals. The findings suggest that as is the case with TD individuals, face processing of individuals with ASD is influenced by differences in visual experience with different face categories.

Visual scanning and recognition of Chinese, Caucasian, and racially ambiguous faces: contributions from bottom-up facial physiognomic information and top-down knowledge of racial categories

Recent studies have shown that participants use different eye movement strategies when scanning own- and other-race faces. However, it is unclear (1) whether this effect is related to face recognition performance, and (2) to what extent this effect is influenced by top-down or bottom-up facial information. In the present study, Chinese participants performed a face recognition task with Chinese, Caucasian, and racially ambiguous faces. For the racially ambiguous faces, we led participants to believe that they were viewing either own-race Chinese faces or other-race Caucasian faces. Results showed that (1) Chinese participants scanned the nose of the true Chinese faces more than that of the true Caucasian faces, whereas they scanned the eyes of the Caucasian faces more than those of the Chinese faces; (2) they scanned the eyes, nose, and mouth equally for the ambiguous faces in the Chinese condition compared with those in the Caucasian condition; (3) when recognizing the true Chinese target faces, but not the true target Caucasian faces, the greater the fixation proportion on the nose, the faster the participants correctly recognized these faces. The same was true when racially ambiguous face stimuli were thought to be Chinese faces. These results provide the first evidence to show that (1) visual scanning patterns of faces are related to own-race face recognition response time, and (2) it is bottom-up facial physiognomic information that mainly contributes to face scanning. However, top-down knowledge of racial categories can influence the relationship between face scanning patterns and recognition response time.

Female face preference in 4-month-olds: the importance of hairline

At 3-4 months of age, infants respond to gender information in human faces. Specifically, young infants display a visual preference toward female over male faces. In three experiments, using a visual preference task, we investigated the role of hairline information in this bias. In Experiment 1, we presented male and female composite faces with similar hairstyles to 4-month-olds and observed a preference for female faces. In Experiment 2, the faces were presented, but in this instance, without hairline cues, and the preference was eliminated. In Experiment 3, using the same cropping to eliminate hairline cues, but with feminized female faces and masculinized male faces, infants' preference toward female faces was still not in evidence. The findings show that hairline information is important in young infants' preferential orientation toward female faces.

The eye-size illusion: psychophysical characteristics, generality, and relation to holistic face processing

Rakover [(2011). In Y. H. Zhang (Ed.), Advances in face image analysis: Techniques and technologies (pp. 316-333). Hershey, PA: IGI Global] observed a novel eye-size illusion: when increasing the size of a face but keeping the size of its eyes unchanged, the eyes are perceived to be smaller than in the original face. Here, we systematically manipulated the face size and found that the magnitude of this illusion linearly changed as a function of the face frame size (experiment 1). Additionally, the same magnitude of an illusion was observed for the perception of the size of the mouth when we changed the face frame but kept the mouth size constant (experiment 2). Further, when the faces and eyes were presented upside down, the magnitude of the illusion was significantly reduced in both Chinese participants (experiment 3) and Caucasian participants (experiment 4). The results suggest that the perception of eye or mouth size occurs in the relational context of the whole face; and when the face is inverted, thereby disrupting holistic processing, the magnitude of the illusion is reduced. We therefore suggest that holistic processing is involved in producing the illusion.

Natural, but not artificial, facial movements elicit the left visual field bias in infant face scanning

A left visual field (LVF) bias has been consistently reported in eye movement patterns when adults look at face stimuli, which reflects hemispheric lateralization of face processing and eye movements. However, the emergence of the LVF attentional bias in infancy is less clear. The present study investigated the emergence and development of the LVF attentional bias in infants from 3 to 9 months of age with moving face stimuli. We specifically examined the naturalness of facial movements in infants'LVF attentional bias by comparing eye movement patterns in naturally and artificially moving faces. Results showed that 3- to 5-month-olds exhibited the LVF attentional bias only in the lower half of naturally moving faces, but not in artificially moving faces. Six- to 9-month-olds showed the LVF attentional bias in both the lower and upper face halves only in naturally moving, but not in artificially moving faces. These results suggest that the LVF attentional bias for face processing may emerge around 3 months of age and is driven by natural facial movements. The LVF attentional bias reflects the role of natural face experience in real life situations that may drive the development of hemispheric lateralization of face processing in infancy.

Both children and adults scan faces of own and other races differently

Extensive behavioral and neural evidence suggests that processing of own-race faces differs from that of other-race faces in both adults and infants. However, little research has examined whether and how children scan faces of own and other races differently for face recognition. In this eye-tracking study, Chinese children aged from 4 to 7 years and Chinese adults were asked to remember Chinese and Caucasian faces. None of the participants had any direct contact with foreign individuals. Multi-method analyses of eye-tracking data revealed that regardless of age group, proportional fixation duration on the eyes of Chinese faces was significantly lower than that on the eyes of Caucasian faces, whereas proportional fixation duration on the nose and mouth of Chinese faces was significantly higher than that on the nose and mouth of Caucasian faces. In addition, the amplitude of saccades on Chinese faces was significantly lower than that on Caucasian faces, potentially reflecting finer-grained processing for own-race faces. Moreover, adults' fixation duration/saccade numbers on the whole faces, proportional fixation percentage on the nose, proportional number of saccades between AOIs, and accuracy in recognizing faces were higher than those of children. These results together demonstrate that an abundance of visual experience with own-race faces and a lack of it with other-race faces may result in differential facial scanning in both children and adults. Furthermore, the increased experience of processing faces may result in a more holistic and advanced scanning strategy in Chinese adults.

The effects of information type (features vs. configuration) and location (eyes vs. mouth) on the development of face perception

The goal of the current study was to investigate the development of face processing strategies in a perceptual discrimination task. Children (7-12 years of age) and young adults were administered the Face Dimensions Task. In the Face Dimensions Task, participants were asked to judge whether two simultaneously presented faces were the "same" or "different". For the "same" trials, the two faces were identical. For the "different" trials, the faces differed in either the spacing between the eyes, the spacing between the nose and the mouth, the size of the eyes, or the size of the mouth. The main finding was that 7- to 10-year-old children showed no difference in their ability to discriminate differences in eye size and eye spacing but showed a poor ability to discriminate differences in nose and mouth spacing and, to a lesser extent, mouth size. The developmental lag between nose-mouth discriminations and the other featural and configural discriminations was reduced in older children and eliminated by young adulthood. These results indicate that the type of face information (i.e., configural vs. featural) and its location (i.e., eye vs. mouth) jointly contribute to the development of face perception abilities.

On the facilitative effects of face motion on face recognition and its development

For the past century, researchers have extensively studied human face processing and its development. These studies have advanced our understanding of not only face processing, but also visual processing in general. However, most of what we know about face processing was investigated using static face images as stimuli. Therefore, an important question arises: to what extent does our understanding of static face processing generalize to face processing in real-life contexts in which faces are mostly moving? The present article addresses this question by examining recent studies on moving face processing to uncover the influence of facial movements on face processing and its development. First, we describe evidence on the facilitative effects of facial movements on face recognition and two related theoretical hypotheses: the supplementary information hypothesis and the representation enhancement hypothesis. We then highlight several recent studies suggesting that facial movements optimize face processing by activating specific face processing strategies that accommodate to task requirements. Lastly, we review the influence of facial movements on the development of face processing in the first year of life. We focus on infants' sensitivity to facial movements and explore the facilitative effects of facial movements on infants' face recognition performance. We conclude by outlining several future directions to investigate moving face processing and emphasize the importance of including dynamic aspects of facial information to further understand face processing in real-life contexts.

On the Links Among Face Processing, Language Processing, and Narrowing During Development

From the beginning of life, face and language processing are crucial for establishing social communication. Studies on the development of systems for processing faces and language have yielded such similarities as perceptual narrowing across both domains. In this article, we review several functions of human communication, and then describe how the tools used to accomplish those functions are modified by perceptual narrowing. We conclude that narrowing is common to all forms of social communication. We argue that during evolution, social communication engaged different perceptual and cognitive systems-face, facial expression, gesture, vocalization, sound, and oral language-that emerged at different times. These systems are interactive and linked to some extent. In this framework, narrowing can be viewed as a way infants adapt to their native social group.

Preference for human eyes in human infants

Despite evidence supporting an early attraction to human faces, the nature of the face representation in neonates and its development during the first year after birth remain poorly understood. One suggestion is that an early preference for human faces reflects an attraction toward human eyes because human eyes are distinctive compared with other animals. In accord with this proposal, prior empirical studies have demonstrated the importance of the eye region in face processing in adults and infants. However, an attraction for the human eye has never been shown directly in infants. The current study aimed to investigate whether an attraction for human eyes would be present in newborns and older infants. With the use of a preferential looking time paradigm, newborns and 3-, 6-, 9-, and 12-month-olds were simultaneously presented with a pair of nonhuman primate faces (chimpanzees and Barbary macaques) that differed only by the eyes, thereby pairing a face with original nonhuman primate eyes with the same face in which the eyes were replaced by human eyes. Our results revealed that no preference was observed in newborns, but a preference for nonhuman primate faces with human eyes emerged from 3months of age and remained stable thereafter. The findings are discussed in terms of how a preference for human eyes may emerge during the first few months after birth.

Own- and other-race face identity recognition in children: the effects of pose and feature composition

We used a matching-to-sample task and manipulated facial pose and feature composition to examine the other-race effect (ORE) in face identity recognition between 5 and 10 years of age. Overall, the present findings provide a genuine measure of own- and other-race face identity recognition in children that is independent of photographic and image processing. The current study also confirms the presence of an ORE in children as young as 5 years of age using a recognition paradigm that is sensitive to their developing cognitive abilities. In addition, the present findings show that with age, increasing experience with familiar classes of own-race faces and further lack of experience with unfamiliar classes of other-race faces serves to maintain the ORE between 5 and 10 years of age rather than exacerbate the effect. All age groups also showed a differential effect of stimulus facial pose in their recognition of the internal regions of own- and other-race faces. Own-race inner faces were remembered best when three-quarter poses were used during familiarization and frontal poses were used during the recognition test. In contrast, other-race inner faces were remembered best when frontal poses were used during familiarization and three-quarter poses were used during the recognition test. Thus, children encode and/or retrieve own- and other-race faces from memory in qualitatively different ways.

Own- and other-race face scanning in infants: implications for perceptual narrowing

The present study investigated how 6- and 9-month-old Caucasian infants scan Caucasian and Chinese dynamic faces using eye-tracking methodology. Analyses of looking times revealed that with increased age, infants decreased their looking time to other-race noses, while maintaining their looking time for own-race noses. From 6 to 9 months, infants increased their looking time for the eyes of both races of faces. Analyses of scan paths showed that infants were no more likely to shift their fixation between the eyes of own-race faces than other-race faces. Similarity between participants' scan paths suggested that facial information was collected more efficiently for own- versus other-race faces at 9 months of age. Combined with previous eye-tracking studies of infants' face scanning (Liu et al. [2011] Journal of Experimental Child Psychology, 108, 180-189; Wheeler et al. [2011] PLoS ONE, 6, e18621. doi: 10.1371/journal.pone.0018621; Xiao et al. [2013] International Journal of Behavioral Development, 37, 100-105), the findings are interpreted in the context of perceptual narrowing and suggest differential contributions of visual experience, facial physiognomy, and culture in accounting for similarity and difference in infants scanning of own- and other-race faces.

Do individuals with and without autism spectrum disorder scan faces differently? A new multi-method look at an existing controversy

Individuals with autism spectrum disorder (ASD) are known to process faces atypically. However, there has been considerable controversy regarding whether ASD individuals also scan faces differently from typical adults. Here we compared ASD individuals' face-scanning patterns with those of typically developing (TD) controls and intellectually disabled (ID) but non-ASD individuals with the use of an eye tracker and multiple approaches to analyze eye-tracking data. First, we analyzed the eye movement data with a traditional approach, measuring fixation duration on each area of interest within the face. We found that compared with TD and ID individuals, ASD individuals looked significantly shorter at the right eye. Second, we used a data-driven method that analyzes fixations on each pixel of the face stimulus and found that individuals with ASD looked more at the central nasal area than TD and ID individuals. Third, we used a novel saccade path analysis that measures frequencies of saccades between major face areas. We found that ASD individuals scanned less often between core facial features than TD individuals but did not differ from ID individuals. Findings from the multi-method approaches show that individuals with ASD appear not to have a pervasive ASD-specific atypicality in visual attention toward the face. The ASD-specific atypical face-scanning patterns were shown to be limited to fixations on the eyes and nose.

Face contour is crucial to the fat face illusion

In 2010 Thompson reported a "fat face thin" illusion that, when next to an inverted face, an upright face looks "fatter". Sun et al (2012 Perception 41 117-120) observed that one of the faces need not be inverted for the illusion to emerge: when two identical faces are presented one above the other, the face at the bottom appears "fatter" than the top one. Neither inverted faces nor clocks induced the illusion. Here we conducted three experiments probing the role that face contour plays in producing the fat face illusion. In experiment 1 line drawing faces were found to induce the illusion, suggesting that face contour is important for producing the illusion. In experiment 2 line drawing faces with scrambled internal features and empty line drawing faces devoid of internal features were found to induce the illusion. In experiment 3 internal face features arranged in their canonical face layout, but not in a scrambled layout, were found to induce the illusion. However, the magnitude of the effect was significantly weaker than the effect obtained for empty face contour in experiment 2. Collectively, these results suggest that a fat face illusion is obtained when there is sufficient information in the stimulus to activate an internal face schema.

Abnormality in face scanning by children with autism spectrum disorder is limited to the eye region: evidence from multi-method analyses of eye tracking data

There has been considerable controversy regarding whether children with autism spectrum disorder (ASD) and typically developing children (TD) show different eye movement patterns when processing faces. We investigated ASD and age- and IQ-matched TD children's scanning of faces using a novel multi-method approach. We found that ASD children spent less time looking at the whole face generally. After controlling for this difference, ASD children's fixations of the other face parts, except for the eye region, and their scanning paths between face parts were comparable either to the age-matched or IQ-matched TD groups. In contrast, in the eye region, ASD children's scanning differed significantly from that of both TD groups: (a) ASD children fixated significantly less on the right eye (from the observer's view); (b) ASD children's fixations were more biased towards the left eye region; and (c) ASD children fixated below the left eye, whereas TD children fixated on the pupil region of the eye. Thus, ASD children do not have a general abnormality in face scanning. Rather, their abnormality is limited to the eye region, likely due to their strong tendency to avoid eye contact.

Developmental Origins of the Other-Race Effect

The other-race effect (ORE) in face recognition refers to better recognition memory for faces of one's own race than faces of another race-a common phenomenon among individuals living in primarily mono-racial societies. In this article, we review findings suggesting that early visual and sociocultural experiences shape one's processing of familiar and unfamiliar race classes and give rise to the ORE within the 1st year of life. However, despite its early development, the ORE can be prevented, attenuated, and even reversed given experience with a novel race class. Social implications of the ORE are discussed in relation to development of race-based preferences for social partners and racial prejudices.

Nine-month-old infants prefer unattractive bodies over attractive bodies

Infant responses to adult-defined unattractive male body shapes versus attractive male body shapes were assessed using visual preference and habituation procedures. Looking behavior indicated that 9-month-olds have a preference for unattractive male body shapes over attractive ones; however, this preference is demonstrated only when head information is obscured. In contrast, 6- and 3.5-month-olds did not show a preference for unattractive or attractive bodies. The 6-month-olds discriminated between the two categories, whereas the 3.5-month-olds did not. Because unattractive body shapes are more common than attractive/athletic body shapes in our everyday environment, a preference for unattractive body shapes at 9 months of age suggests that preferences for particular human body shapes reflect level of exposure and familiarity rather than culturally defined stereotypes of body attractiveness.

Development of face scanning for own- and other-race faces in infancy

The present study investigated whether infants visually scan own- and other-race faces differently as well as how these differences in face scanning develop with age. A multi-method approach was used to analyze the eye-tracking data of 6- and 9-month-old Caucasian infants scanning dynamically displayed own- and other-race faces. We found that 6-month-olds showed differential fixation, fixating significantly more on the left eye and mouth of own-race faces, but more on the nose of other-race faces. Infants at 9 months of age fixated more on the eyes of own-race faces, but more on the mouth of other-race faces. A scan path analysis revealed that infants shifted their attention between the eyes of the own-race faces significantly more frequently than for other-race faces. Overall, younger and older infants responded differentially to own- versus other-race faces not only in the absolute amount of time spent fixating specific features, but also on their fixation shifts between features.