The development of perceptual sensitivity to second-order facial relations in children

The development of processing second-order spatial relations of faces in Chinese preschoolers

Second-order relational information processing is the perception of the relative distance between facial features. Previous studies ignored the effect of different spatial manipulations on second-order sensitivity in face processing, and little is known about its developmental trajectory in East Asian populations, who have stronger holistic face processing than Western populations. We addressed these gaps in the literature through an experiment with four groups of Chinese preschool children (aged 3-6 years; n = 157) and a group of adults (n = 25). The participants were presented with face pairs displaying features with various spatial distance manipulations (Change 1: changes in the spacing between eyes; Change 2: nose-mouth spacing changes; Change 3: a combination of Changes 1 and 2) using a simultaneous two-alternative forced-choice task. Second-order sensitivity was already present in 3-year-old children across all manipulations and became more pronounced in 4-year-old children. Second-order sensitivity to the spatial distance between the eyes (i.e., Changes 1 and 3) among 4-year-olds was higher than that of 3-year-olds and was similar to that of adults, suggesting a key increase of this sensitivity from 3 to 4 years of age. Regarding the Change 2 condition, preschoolers aged 5 and 6 years had higher sensitivity than 3-year-olds; however, all preschoolers' sensitivity was inferior to that of adults. These findings show that the development of Chinese preschoolers' sensitivity for detecting spatial relations between the eyes might be faster than that for detecting nose-mouth spacing, supporting the importance of eyes in face processing.

Configural properties of face portraits change between childhood and adulthood

Adult observers are sensitive to the configuration of facial features within a face, able to distinguish between relative differences in feature spacing, and detecting deviations from typical facial appearance. How does the representation of the typical configuration of facial features develop? While there is a great deal of work describing children’s developing abilities to detect differences in feature spacing across face images, there is substantially less work examining what children think constitutes a typical arrangement of facial features. In the current study, we investigated this issue using a production task in which adults and 5- to 10-year-old children created a face “portrait” by arranging the eyes, nose, and mouth of a standard face within an empty outline. Using this simple task, we found differences in face configuration across age groups, such that children of all ages made far larger errors than adult participants, expanding facial features outward from the center of the face more than adults. These results were not affected by face inversion, potentially implying a domain-general rather than face-specific process. We also found that children of all ages endorsed the correct configuration as a best likeness in a perceptual task. We discuss these results in terms of ongoing debate regarding the extent to which configural processing is a meaningful component of face recognition and the conclusions we can draw from production paradigms as compared to purely perceptual tasks.

Learning faces from variability: Four- and five-year-olds differ from older children and adults

Children under 6 years of age have difficulty recognizing a familiar face across changes in appearance and telling the face apart from similar-looking people. Understanding the process by which newly encountered faces become familiar can provide insights into these difficulties. Exposure to the ways in which a person varies in appearance is one mechanism by which adults and older children (≥6 years) learn new faces. We provide the first investigation of whether this mechanism for face learning functions in younger children. Children aged 4 and 5 years were read two storybooks featuring an unfamiliar character. Participants viewed six images of the character in one story and one image of the character in the other story. After each story, children were asked to identify novel images of the character that were intermixed with images of a similar-looking distractor. Like older children, 4- and 5-year-olds were more sensitive to identity in the 6-image condition, but they also adapted a less conservative criterion. Young children identified more images of the character after viewing six images versus one image. However, many also incorrectly identified more images of the distractor after viewing six images versus one image, an effect not previously found for older children and adults. These results suggest that this mechanism for face learning is not fully refined before 6 years of age.

Early monocular enucleation selectively disrupts neural development of face perception in the occipital face area

Retinoblastoma generally occurs before 5 years of age and often requires enucleation (surgical removal of one eye) of the cancerous eye. We have previously shown using behavioural methods that this disruption in binocular vision during the critical period of visual development results in impaired face perception. In this case series study, we sought to determine the underlying neural correlates of this face perception deficit by examining brain activity in regions of cortex that preferentially respond to visual images of faces and places in 6 adults who had one eye enucleated early in life due to retinoblastoma. A group of 10 binocularly-intact adult controls were recruited for comparison. Functional magnetic resonance imaging (fMRI) was conducted over two separate runs for each participant in one scanning session. Each run consisted of 6 blocks each of face, place, and object images. Region-of-interest analyses were conducted to locate face-preferential [fusiform face area (FFA), occipital face area (OFA)] and place-preferential [parahippocampal place area (PPA), transverse occipital sulcus (TOS)] regions-of-interest. Descriptive statistics are reported. Results. Enucleated adults exhibited reduced functional activation in face-preferential regions (left FFA, right OFA, left OFA), but similar activation within the face-preferential right FFA and the place-preferential regions (bilateral PPA and TOS). Conclusions. These results indicate that early monocular enucleation prevents robust development of late-maturing face processing capabilities and that this disruption is specific to face networks and not to networks supporting other visual image categories.

Timing Is Almost Everything: How Children Perceive and Act on Dynamic Affordances

A key challenge for the developing perception-action system is learning how to move the self in relation to other moving objects. This often involves perceiving and acting on affordances or possibilities for action that depend on the relation between the characteristics of the individual and the properties of the environment (Gibson, 1979). This chapter overviews our program of research on perceiving and acting on dynamic affordances (i.e., possibilities for action that vary over time). Our goal is to bridge the divide between basic and applied research by using road crossing as a model system for studying how children's ability to perceive and act on dynamic affordances undergoes change with age and experience. The basic task is for participants to cross virtual roads with continuous traffic either on foot or on a bicycle. This work reveals that children's gap choices and crossing motions are less tightly linked than those of adults. Children often choose the same size gaps as adults but time their entry into those gaps less tightly than adults. As a result, children typically end up with less time to spare than adults when they clear the path of the vehicles. Improvement in gap selection and movement timing occurs gradually over development, indicating the perception-action system undergoes continuous change well into adolescence. As in other areas of development (e.g., face perception, word recognition), this kind of gradual developmental change appears critical for the fine-tuning of the system. The late development of these skills may explain also why adolescent pedestrians, cyclists, and drivers continue to be at risk for collisions when crossing roads. Further work aimed at better understanding the developmental mechanisms underlying these changes will inform the fields of both developmental science and injury prevention.

Getting to know you: The development of mechanisms underlying face learning

Nearly every study investigating the development of face recognition has focused on the ability to tell people apart using one or two tightly controlled images to represent each identity. Such research ignores the challenge of recognizing the same person despite variability in appearance. Whereas natural variation in appearance makes unfamiliar faces difficult to recognize, by 6 years of age people easily recognize multiple images of familiar faces. Two mechanisms are proposed to underlie the process by which adults become familiar with newly encountered faces. We provide the first examination of the development of these mechanisms during childhood (6-11 years). In Experiment 1, we examined children's (6- to 10-year-olds') and adults' ability to engage in ensemble coding-the ability to rapidly extract an average representation of an identity from several instances. In Experiment 2, we examined children's ability to use within-person variability in appearance to recognize novel instances of a newly encountered identity. We created a child-friendly perceptual matching task, and the number of images to which participants were exposed varied across targets. Although children were less accurate than adults overall in Experiment 2, we found no age-related improvement in either ensemble coding or the ability to benefit from exposure to within-person variability in appearance when learning a new face, suggesting that both abilities are developed by 6 years of age. We discuss the implications of these findings for understanding the nature of mechanisms underlying face learning and other developmental processes such as language and music.

How does a newly encountered face become familiar? The effect of within-person variability on adults' and children's perception of identity

Adults and children aged 6years and older easily recognize multiple images of a familiar face, but often perceive two images of an unfamiliar face as belonging to different identities. Here we examined the process by which a newly encountered face becomes familiar, defined as accurate recognition of multiple images that capture natural within-person variability in appearance. In Experiment 1 we examined whether exposure to within-person variability in appearance helps children learn a new face. Children aged 6-13years watched a 10-min video of a woman reading a story; she was filmed on a single day (low variability) or over three days, across which her appearance and filming conditions (e.g., camera, lighting) varied (high variability). After familiarization, participants sorted a set of images comprising novel images of the target identity intermixed with distractors. Compared to participants who received no familiarization, children showed evidence of learning only in the high-variability condition, in contrast to adults who showed evidence of learning in both the low- and high-variability conditions. Experiment 2 highlighted the efficiency with which adults learn a new face; their accuracy was comparable across training conditions despite variability in duration (1 vs. 10min) and type (video vs. static images) of training. Collectively, our findings show that exposure to variability leads to the formation of a robust representation of facial identity, consistent with perceptual learning in other domains (e.g., language), and that the development of face learning is protracted throughout childhood. We discuss possible underlying mechanisms.

Selectivity of Face Perception to Horizontal Information over Lifespan (from 6 to 74 Year Old)

Face recognition in young human adults preferentially relies on the processing of horizontally-oriented visual information. We addressed whether the horizontal tuning of face perception is modulated by the extensive experience humans acquire with faces over the lifespan, or whether it reflects an invariable processing bias for this visual category. We tested 296 subjects aged from 6 to 74 years in a face matching task. Stimuli were upright and inverted faces filtered to preserve information in the horizontal or vertical orientation, or both (HV) ranges. The reliance on face-specific processing was inferred based on the face inversion effect (FIE). FIE size increased linearly until young adulthood in the horizontal but not the vertical orientation range of face information. These findings indicate that the protracted specialization of the face processing system relies on the extensive experience humans acquire at encoding the horizontal information conveyed by upright faces.

Developmental changes in analytic and holistic processes in face perception

Although infants demonstrate sensitivity to some kinds of perceptual information in faces, many face capacities continue to develop throughout childhood. One debate is the degree to which children perceive faces analytically versus holistically and how these processes undergo developmental change. In the present study, school-aged children and adults performed a perceptual matching task with upright and inverted face and house pairs that varied in similarity of featural or 2(nd) order configural information. Holistic processing was operationalized as the degree of serial processing when discriminating faces and houses [i.e., increased reaction time (RT), as more features or spacing relations were shared between stimuli]. Analytical processing was operationalized as the degree of parallel processing (or no change in RT as a function of greater similarity of features or spatial relations). Adults showed the most evidence for holistic processing (most strongly for 2(nd) order faces) and holistic processing was weaker for inverted faces and houses. Younger children (6-8 years), in contrast, showed analytical processing across all experimental manipulations. Older children (9-11 years) showed an intermediate pattern with a trend toward holistic processing of 2(nd) order faces like adults, but parallel processing in other experimental conditions like younger children. These findings indicate that holistic face representations emerge around 10 years of age. In adults both 2(nd) order and featural information are incorporated into holistic representations, whereas older children only incorporate 2(nd) order information. Holistic processing was not evident in younger children. Hence, the development of holistic face representations relies on 2(nd) order processing initially then incorporates featural information by adulthood.

The PCA learning effect: An emerging correlate of face memory during childhood

Human adults implicitly learn the prototype and the principal components of the variability distinguishing faces (Gao & Wilson, 2014). Here we measured the implicit learning effect in adults and 9-year-olds, and with a modified child-friendly procedure, in 7-year-olds. All age groups showed the implicit learning effect by falsely recognizing the average (the prototype effect) and the principal component faces as having been seen (the PCA learning effect). The PCA learning effect, but not the prototype effect increased between 9years of age and adulthood and at both ages was the better predictor of memory for the actually studied faces. In contrast, for the 7-year-olds, the better predictor of face memory was the prototype effect. The pattern suggests that there may be a developmental change between ages 7 and 9 in the mechanism underlying memory for faces. We provide the first evidence that children as young as age 7 can extract the most important dimensions of variation represented by principal components among individual faces, a key ability that grows stronger with age and comes to underlie memory for faces.

The processing of facial identity and expression is interactive, but dependent on task and experience

Facial identity and emotional expression are two important sources of information for daily social interaction. However the link between these two aspects of face processing has been the focus of an unresolved debate for the past three decades. Three views have been advocated: (1) separate and parallel processing of identity and emotional expression signals derived from faces; (2) asymmetric processing with the computation of emotion in faces depending on facial identity coding but not vice versa; and (3) integrated processing of facial identity and emotion. We present studies with healthy participants that primarily apply methods from mathematical psychology, formally testing the relations between the processing of facial identity and emotion. Specifically, we focused on the "Garner" paradigm, the composite face effect and the divided attention tasks. We further ask whether the architecture of face-related processes is fixed or flexible and whether (and how) it can be shaped by experience. We conclude that formal methods of testing the relations between processes show that the processing of facial identity and expressions interact, and hence are not fully independent. We further demonstrate that the architecture of the relations depends on experience; where experience leads to higher degree of inter-dependence in the processing of identity and expressions. We propose that this change occurs as integrative processes are more efficient than parallel. Finally, we argue that the dynamic aspects of face processing need to be incorporated into theories in this field.

Developmental Trajectory of Face Processing Revealed by Integrative Dynamics

Given their unique connectivity, a primary function of brain networks must be to transfer and integrate information. Therefore, the way in which information is integrated by individual nodes of the network may be an informative aspect of cognitive processing. Here we present a method inspired by telecommunications research that utilizes time–frequency fluctuations of neural activity to infer how information is integrated by individual nodes of the network. We use a queueing theoretical model to interpret empirical data in terms of information processing and integration. In particular, we demonstrate, in participants aged from 6 to 41 years, that the well-known face inversion phenomenon may be explained in terms of information integration. Our model suggests that inverted faces may be associated with shorter and more frequent neural integrative stages, indicating fractured processing and consistent with the notion that inverted faces are perceived by parts. Conversely, our model suggests that upright faces may be associated with a smaller number of sustained episodes of integration, indicating more involved processing, akin to holistic and configural processing. These differences in how upright and inverted faces are processed became more pronounced during development, indicating a gradual specialization for face perception. These effects were robustly expressed in the right fusiform gyrus (all groups), as well as right parahippocampal gyrus (children and adolescents only) and left inferior temporal cortex (adults only).

Attractiveness judgments and discrimination of mommies and grandmas: perceptual tuning for young adult faces

Adults are more accurate in detecting deviations from normality in young adult faces than in older adult faces despite exhibiting comparable accuracy in discriminating both face ages. This deficit in judging the normality of older faces may be due to reliance on a face space optimized for the dimensions of young adult faces, perhaps because of early and continuous experience with young adult faces. Here we examined the emergence of this young adult face bias by testing 3- and 7-year-old children on a child-friendly version of the task used to test adults. In an attractiveness judgment task, children viewed young and older adult face pairs; each pair consisted of an unaltered face and a distorted face of the same identity. Children pointed to the prettiest face, which served as a measure of their sensitivity to the dimensions on which faces vary relative to a norm. To examine whether biases in the attractiveness task were specific to deficits in referencing a norm or extended to impaired discrimination, we tested children on a simultaneous match-to-sample task with the same stimuli. Both age groups were more accurate in judging the attractiveness of young faces relative to older faces; however, unlike adults, the young adult face bias extended to the match-to-sample task. These results suggest that by 3 years of age, children's perceptual system is more finely tuned for young adult faces than for older adult faces, which may support past findings of superior recognition for young adult faces.

Category-specific face prototypes are emerging, but not yet mature, in 5-year-old children

Adults' expertise in face recognition has been attributed to norm-based coding. Moreover, adults possess separable norms for a variety of face categories (e.g., race, sex, age) that appear to enhance recognition by reducing redundancy in the information shared by faces and ensuring that only relevant dimensions are used to encode faces from a given category. Although 5-year-old children process own-race faces using norm-based coding, little is known about the organization and refinement of their face space. The current study investigated whether 5-year-olds rely on category-specific norms and whether experience facilitates the development of dissociable face prototypes. In Experiment 1, we examined whether Chinese 5-year-olds show race-contingent opposing aftereffects and the extent to which aftereffects transfer across face race among Caucasian and Chinese 5-year-olds. Both participant races showed partial transfer of aftereffects across face race; however, there was no evidence for race-contingent opposing aftereffects. To examine whether experience facilitates the development of category-specific prototypes, we investigated whether race-contingent aftereffects are present among Caucasian 5-year-olds with abundant exposure to Chinese faces (Experiment 2) and then tested separate groups of 5-year-olds with two other categories with which they have considerable experience: sex (male/female faces) and age (adult/child faces) (Experiment 3). Across all three categories, 5-year-olds showed no category-contingent opposing aftereffects. These results demonstrate that 5 years of age is a stage characterized by minimal separation in the norms and associated coding dimensions used for faces from different categories and suggest that refinement of the mechanisms that underlie expert face processing occurs throughout childhood.

Developmental changes in facial expression recognition in Japanese school-age children

PURPOSE

Facial expressions hold abundant information and play a central part in communication. In daily life, we must construct amicable interpersonal relationships by communicating through verbal and nonverbal behaviors. While school-age is a period of rapid social growth, few studies exist that study developmental changes in facial expression recognition during this age. This study investigated developmental changes in facial expression recognition by examining observers' gaze on others' expressions.

SUBJECTS

87 school-age children from first to sixth grade (41 boys, 46 girls).

METHOD

The Tobii T60 Eye-tracker(Tobii Technologies, Sweden) was used to gauge eye movement during a task of matching pre-instructed emotion words and facial expressions images (neutral, angry, happy, surprised, sad, disgusted) presented on a monitor fixed at a distance of 50 cm.

RESULTS

In the task of matching the six facial expression images and emotion words, the mid- and higher-grade children answered more accurately than the lower-grade children in matching four expressions, excluding neutral and happy. For fixation time and fixation count, the lower-grade children scored lower than other grade children, gazing on all facial expressions significantly fewer times and for shorter periods.

CONCLUSION

It is guessed that the stage from lower grades to middle grades is a turning point in facial recognition.

The influence of symmetry on children's judgments of facial attractiveness

In experiment 1, we examined developmental changes in the influence of symmetry on judgments of attractiveness by showing adults and children pairs of individual faces in which one face was transformed 75% toward perfect symmetry, while the other face was transformed by exaggerating its asymmetries by 75%. Adults and 9-year-olds, but not 5-year-olds, rated the more symmetric faces as more attractive than the less symmetric faces, although the effect was stronger in adults than 9-year-olds. The preference for symmetry was stronger for male than female faces, and stronger for adults' than children's faces. In experiment 2, comparisons of the symmetry of the original male and female faces revealed no measured differences but lower ratings by adults of symmetry in the male faces. Overall, the results suggest that the influence of symmetry on attractiveness judgments emerges after the age of 5 years, and matures after the age of 9 years. The stronger effects for adult viewers may reflect an increase in sensitivity to symmetry as experience with faces increases and/or as the visual system matures. As well, attractiveness may become more salient after puberty, so that honest signals of mate quality, such as symmetry, have a stronger effect for adult viewers, especially when judging adult faces.

Sensitivity to spacing information increases more for the eye region than for the mouth region during childhood

Sensitivity to spacing information within faces improves with age and reaches maturity only at adolescence. In this study, we tested 6–16-year-old children’s sensitivity to vertical spacing when the eyes or the mouth is the facial feature selectively manipulated. Despite the similar discriminability of these manipulations when they are embedded in inverted faces (Experiment 1), children’s sensitivity to spacing information manipulated in upright faces improved with age only when the eye region was concerned (Experiment 2). Moreover, children’s ability to process the eye region did not correlate with their selective visual attention, marking the automation of the mechanism (Experiment 2). In line with recent findings, we suggest here that children rely on a holistic/configural face processing mechanism to process the eye region, composed of multiple features to integrate, which steadily improves with age.

Development of Recognition of Face Parts from Unfamiliar Faces

The present study examined developmental changes in the ability to recognize face parts. In Experiment 1, participants were familiarized with whole faces and given a recognition test with old and new eyes, noses, mouths, inner faces, outer faces, or whole faces. Adults were above chance in their recognition of the eye and mouth regions. However, children did not naturally encode and recognize face parts independently of the entire face. In addition, all age groups showed comparable inner and outer face recognition, except for 8- to 9-year-olds who showed a recognition advantage for outer faces. In Experiment 2, when participants were familiarized with eyes, noses, or mouths and tested with eyes, noses, or mouths, respectively, all ages showed above-chance recognition of eyes and mouths. Thirteen- to 14-year-olds were adult-like in their recognition of the eye region, but mouth recognition continued to develop beyond 14 years of age. Nose recognition was above chance among 13- to 14-year-olds, but recognition scores remained low even in adulthood. The present findings reveal unique developmental trajectories in the use of isolated facial regions in face recognition and suggest that featural cues (as a class) have a different ontogenetic course relative to holistic and configural cues.

A critical review of the development of face recognition: experience is less important than previously believed

Historically, it has been argued that face individuation develops very slowly, not reaching adult levels until adolescence, with experience being the driving force behind this protracted improvement. Here, we challenge this view based on extensive review of behavioural and neural findings. Results demonstrate qualitative presence of all key phenomena related to face individuation (encoding of novel faces, holistic processing effects, face-space effects, face-selective responses in neuroimaging) at the earliest ages tested, typically 3-5 years of age and in many cases even infancy. Results further argue for quantitative maturity by early childhood, based on an increasing number of behavioural studies that have avoided the common methodological problem of restriction of range, as well as event-related potential (ERP), but not functional magnetic resonance imaging (fMRI) studies. We raise a new possibility that could account for the discrepant fMRI findings-namely, the use of adult-sized head coils on child-sized heads. We review genetic and innate contributions to face individuation (twin studies, neonates, visually deprived monkeys, critical periods, perceptual narrowing). We conclude that the role of experience in the development of the mechanisms of face identification has been overestimated. The emerging picture is that the mechanisms supporting face individuation are mature early, consistent with the social needs of children for reliable person identification in everyday life, and are also driven to an important extent by our evolutionary history.