Recognizing the Face of Johnny, Suzy, and Me: Insensitivity to the Spacing Among Features at 4 Years of Age

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.

Children's ability to recognize their parent's face improves with age

Adults are experts at recognizing familiar faces across images that incorporate natural within-person variability in appearance (i.e., ambient images). Little is known about children's ability to do so. In the current study, we investigated whether 4- to 7-year-olds (n = 56) could recognize images of their own parent-a person with whom children have had abundant exposure in a variety of different contexts. Children were asked to identify images of their parent that were intermixed with images of other people. We included images of each parent taken both before and after their child was born to manipulate how close the images were to the child's own experience. When viewing before-birth images, 4- and 5-year-olds were less sensitive to identity than were older children; sensitivity did not differ when viewing images taken after the child was born. These findings suggest that with even the most familiar face, 4- and 5-year-olds have difficulty recognizing instances that go beyond their direct experience. We discuss two factors that may contribute to the prolonged development of familiar face recognition.

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.

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 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.

Intact facial adaptation in autistic adults

Adaptation paradigms seek to bias subsequently viewed stimuli through prolonged exposure to an adapting stimulus, thereby giving rise to an aftereffect. Recent experiments have found that children with autism spectrum disorders (ASD) show reduced facial aftereffects, prompting some researchers to speculate that all individuals with ASD exhibit deficient facial adaptation. However, caution is required when generalizing findings from samples of children with ASD to the wider ASD population. The reduced facial aftereffects seen in child samples may instead reflect delayed or atypical developmental trajectories, whereby individuals with ASD are slower to develop adaptive mechanisms. In the present study, two experiments were conducted to determine whether high-functioning adults with ASD also show diminished aftereffects for facial identity and expression. In Experiment 1, using a procedure that minimized the contribution of low-level retinotopic adaptation, we observed substantial aftereffects comparable to those seen in matched controls, for both facial identity and expression. A similar pattern of results was seen in Experiment 2 using a revised procedure that increased the contribution of retinotopic adaptation to the facial aftereffects observed. That adults with autism can show robust facial aftereffects raises the possibility that group differences are seen only at particular points during development, and may not be a lifelong feature of the condition.

Intersensory redundancy hinders face discrimination in preschool children: evidence for visual facilitation

Although infants and children show impressive face-processing skills, little research has focused on the conditions that facilitate versus impair face perception. According to the intersensory redundancy hypothesis (IRH), face discrimination, which relies on detection of visual featural information, should be impaired in the context of intersensory redundancy provided by audiovisual speech and enhanced when intersensory redundancy is absent. Evidence of this visual facilitation and intersensory interference was found in a recent study of 2-month-old infants (Bahrick, Lickliter, & Castellanos, in press). The present study is the first to extend tests of this principle of the IRH to children. Using a more difficult face recognition task in the context of a story, results from 4-year-old children paralleled those of infants and demonstrate that face discrimination in children is also facilitated by dynamic, visual-only exposure, in the absence of intersensory redundancy.

The face inversion effect in infants is driven by high, and not low, spatial frequencies

To investigate the mechanisms underlying development of upright face preferences in infants, the current study measured inversion effects for faces that were spatial frequency (SF) filtered, into low SF and high SF, with the notion that different SFs are analyzed by different visual mechanisms. For comparison to faces, we used object stimuli that consisted of pictures of strollers. In 4 month olds, 8 month olds, and adults, we measured the strength of the selective face inversion effect (sFIE), operationally defined as an upright over inverted looking preference that is greater for faces than objects. In Study 1, we employed unfiltered stimuli, and found a clear sFIE in both infants and adults. To determine what drove this sFIE, in Study 2, the sFIE was measured for low-SF and high-SF stimuli, with all stimuli being equated for visibility. For adults, the sFIE was equally strong for low-SF and high-SF stimuli. A different pattern was seen for infants. Infants exhibited a significantly greater sFIE for high-SF, than for low-SF, stimuli (and only for high SF was the sFIE significant). In fact, the strength of infants' upright face preference for high-SF stimuli was indistinguishable from that observed for unfiltered faces, indicating that in natural (unfiltered) stimuli, high SFs are sufficient to account for infants' upright face preferences.

Inferring emotions from speech prosody: not so easy at age five

Previous research has suggested that children do not rely on prosody to infer a speaker's emotional state because of biases toward lexical content or situational context. We hypothesized that there are actually no such biases and that young children simply have trouble in using emotional prosody. Sixty children from 5 to 13 years of age had to judge the emotional state of a happy or sad speaker and then to verbally explain their judgment. Lexical content and situational context were devoid of emotional valence. Results showed that prosody alone did not enable the children to infer emotions at age 5, and was still not fully mastered at age 13. Instead, they relied on contextual information despite the fact that this cue had no emotional valence. These results support the hypothesis that prosody is difficult to interpret for young children and that this cue plays only a subordinate role up until adolescence to infer others' emotions.

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.

The changing landscape of functional brain networks for face processing in typical development

Greater expertise for faces in adults than in children may be achieved by a dynamic interplay of functional segregation and integration of brain regions throughout development. The present study examined developmental changes in face network functional connectivity in children (5-12 years) and adults (18-43 years) during face-viewing using a graph-theory approach. A face-specific developmental change involved connectivity of the right occipital face area. During childhood, this node increased in strength and within-module clustering based on positive connectivity. These changes reflect an important role of the ROFA in segregation of function during childhood. In addition, strength and diversity of connections within a module that included primary visual areas (left and right calcarine) and limbic regions (left hippocampus and right inferior orbitofrontal cortex) increased from childhood to adulthood, reflecting increased visuo-limbic integration. This integration was pronounced for faces but also emerged for natural objects. Taken together, the primary face-specific developmental changes involved segregation of a posterior visual module during childhood, possibly implicated in early stage perceptual face processing, and greater integration of visuo-limbic connections from childhood to adulthood, which may reflect processing related to development of perceptual expertise for individuation of faces and other visually homogenous categories.

Discrimination of facial features by adults, 10-year-olds, and cataract-reversal patients

In previous studies we created 8 new versions of a single face: 4 differed only in the spacing among features and 4 differed in the shape of the eyes and mouth. Compared to the spacing set, results for this feature set indicated little impairment by inversion, earlier adult-like accuracy (Mondloch et al, 2002 Perception 31 553-566), and normal performance after a history of early visual deprivation from bilateral congenital cataract (Le Grand et al, 2001 Nature 410 890, 412 786). Here we addressed the possibility that this pattern might have resulted from our having inadvertently selected easily discriminated features or including some faces with make-up. We created 20 featural versions of a single female face and asked adults, 10-year-old children, and patients treated for bilateral congenital cataract to make same/different judgments for 120 pairings (half different). The results confirm that adults easily discriminate facial features, even after early visual deprivation from cataract, and that inversion has only a small effect. By the age of 10 years, children are close to, but not quite at, adult levels of accuracy. The previous findings cannot be attributed to our having inadvertently created a feature set that was unusually easy to discriminate.

The effect of face orientation on holistic processing

Holistic processing, a hallmark of face processing, can be measured by the composite face effect: adults have difficulty recognising the top half of a face when it is aligned with a new bottom half, unless holistic processing is disrupted by misaligning the two halves. Like the recognition of facial identity, holistic processing is impaired when faces are inverted. To obtain a more refined measure of the influence of orientation on holistic face processing, we administered the composite face task to adults at each of seven orientations. In both experiment 1 (in which orientations were randomly intermixed) and experiment 2 (in which orientations were blocked), the composite face effect decreased linearly with rotation. We conclude that holistic processing is tuned to upright faces, diminishes as faces deviate from upright, and becomes insignificant once faces reach a sideways orientation. We propose a hierarchical model of face perception in which linear decreases in holistic processing underlie qualitative shifts in other aspects of face perception.

The effect of categorisation on sensitivity to second-order relations in novel objects

Adults appear to be more sensitive to configural information, including second-order relations (the spacing of features), in faces than in other objects. Superior processing of second-order relations in faces may arise from our experience of identifying faces at the individual level of categorisation (eg Bob versus John) but other objects at the basic level of categorisation (eg table versus chair; Gauthier and Tarr, 1997 Vision Research 37 1673- 1682). We simulated this learning difference with novel stimuli (comprised of blobs) by having two groups view the same stimuli but learn to identify the objects only at the basic level (based on the number of constituent blobs) or at both the basic level and individual level (based on the spacing, or second-order relations, of the blobs) of categorisation. Results from two experiments showed that, after training, observers in the individual-level training group were more sensitive to the second-order relations in novel exemplars of the learned category than observers in the basic-level training group. This is the first demonstration of specific improvement in sensitivity to second-order relations after training with non-face stimuli. The findings are consistent with the hypothesis that adults are more sensitive to second-order relations in faces than in other objects, at least in part, because they have more experience identifying faces at the individual level of categorisation.

Featural and configural face processing differentially modulate ERP components

Since all faces share the same first-order configuration, individual faces are recognized by subtle differences in their individual features and second-order configuration. This study asked two questions about the ERP signatures of featural and configural face processing. First, which ERP components are sensitive to subtle modifications of features and second-order configuration? Secondly, does explicitly instructing participants to attend to either the features or the configuration of face stimuli influence the neural processes elicited by these stimuli? In the first part of this experiment, pairs of faces with differences in their features, in their second-order configuration or no difference were presented, with participants making same/different judgments. In the second part, participants were asked to focus on either the features or configuration in pairs of faces and to judge if there was any difference in that aspect while ignoring other differences. The P1 and N170 ERP components were not influenced by feature or second-order configuration differences in faces, indicating that these components could be more sensitive to manipulations that disrupt the first-order configuration of a face. In contrast, the P2 was larger in amplitude for faces with a configuration modification than for faces with a feature modification or for the original face. One explanation of these results is that processing the configuration of a face elicits more visual cortical feedback than processing the features. Finally, modulation of the P300 confirmed that the tasks presented in Part 2 were successful in varying the attention focus on the features or configuration.

An inner face advantage in children's recognition of familiar peers

Children's recognition of familiar own-age peers was investigated. Chinese children (4-, 8-, and 14-year-olds) were asked to identify their classmates from photographs showing the entire face, the internal facial features only, the external facial features only, or the eyes, nose, or mouth only. Participants from all age groups were familiar with the faces used as stimuli for 1 academic year. The results showed that children from all age groups demonstrated an advantage for recognition of the internal facial features relative to their recognition of the external facial features. Thus, previous observations of a shift in reliance from external to internal facial features can be attributed to experience with faces rather than to age-related changes in face processing.

Sleeper effects

Early experience preserves and refines many capabilities that emerge prenatally. Here we describe another role that it plays -- establishing the neural substrate for capabilities that emerge at a much later point in development. The evidence comes from sleeper effects: permanent deficits when early experience was absent in capabilities that normally emerge long after birth. We provide evidence of sleeper effects for three aspects of vision, based on our research with children who were deprived of early visual input by congenital cataracts: contrast sensitivity for mid and high spatial frequencies, holistic face processing, and the ability to recognize the identity of faces based on small differences in the spacing among facial features.

The development of expert face processing: are infants sensitive to normal differences in second-order relational information?

Sensitivity to second-order relational information (i.e., spatial relations among features such as the distance between eyes) is a vital part of achieving expertise with face processing. Prior research is unclear on whether infants are sensitive to second-order differences seen in typical human populations. In the current experiments, we examined whether infants are sensitive to changes in the space between the eyes and between the nose and the mouth that are within the normal range of variability in Caucasian female faces. In Experiment 1, 7-month-olds detected these changes in second-order relational information. Experiment 2 extended this finding to 5-month-olds and also found that infants detect second-order relations in upright faces but not in inverted faces, thereby exhibiting an inversion effect that has been considered to be a hallmark of second-order relational processing during adulthood. These results suggest that infants as young as 5 months are sensitive to second-order relational changes that are within the normal range of human variability. They also indicate that at least rudimentary aspects of face processing expertise are available early in life.

Parental Investment and Resemblance: Replications, Refinements, and Revisions

Evolutionary theory predicts that men should be more concerned with issues of false paternity than women should be concerned with false maternity. In an earlier study ( Volk and Quinsey, 2002 ), we studied how infant cues of resemblance influenced adults' hypothetical adoption decisions. We found that self-perceived cues of resemblance were significantly more important in men's decisions than in women's. Since that study was published, conflicting results have been reported regarding a sex-difference in the importance of cues of resemblance for adoption preference. We therefore sought to replicate our findings in three new studies. In all three studies, we replicated the initial finding of a larger correlation between ratings of resemblance and ratings of adoption preference among men than among women. We also found a trend towards slightly higher global resemblance scores in younger children, suggesting that adults view infants as more anonymous and/or less uniquely distinctive than older children. However, there was wide variance in both the global resemblance and developmental changes in resemblance amongst the different child stimuli used.

Effects of early visual deprivation on perceptual and cognitive development

During early infancy, visual capabilities are quite limited. Nevertheless, patterned visual input during this period is necessary for the later development of normal vision for some, but not all, aspects of visual perception. The evidence comes from studies of children who missed early visual input because it was blocked by dense, central cataracts in both eyes. In this article, we review the effects of bilateral congenital cataracts on two aspects of low-level vision--acuity and contrast sensitivity, and on three aspects of higher-level processing of faces. We end by discussing the implications for understanding the developmental mechanisms underlying normal perceptual and cognitive development.

Developmental changes in perceptions of attractiveness: a role of experience?

In three experiments, we traced the development of the adult pattern of judgments of attractiveness for faces that have been altered to have internal features in low, average, or high positions. Twelve-year-olds and adults demonstrated identical patterns of results: they rated faces with features in an average location as significantly more attractive than faces with either low or high features. Although both 4-year-olds and 9-year-olds rated faces with high features as least attractive, unlike adults and 12-year-olds, they rated faces with low and average features as equally attractive. Three-year-olds with high levels of peer interaction, but not those with low levels of peer interaction, chose faces with low features as significantly more attractive than those with high-placed features, possibly as a result of their increased experience with the proportions of the faces of peers. Overall, the pattern of results is consistent with the hypothesis that experience influences perceptions of attractiveness, with the proportions of the faces participants see in their everyday lives influencing their perceptions of attractiveness.