Tolerance of geometric distortions in infant's face recognition

The aim of the current study is to reveal the effect of global linear transformations (shearing, horizontal stretching, and vertical stretching) on the recognition of familiar faces (e.g., a mother's face) in 6- to 7-month-old infants. In this experiment, we applied the global linear transformations to both the infants’ own mother's face and to a stranger's face, and we tested infants’ preference between these faces. We found that only 7-month-old infants maintained preference for their own mother's face during the presentation of vertical stretching, while the preference for the mother's face disappeared during the presentation of shearing or horizontal stretching. These findings suggest that 7-month-old infants might not recognize faces based on calculating the absolute distance between facial features, and that the vertical dimension of facial features might be more related to infants’ face recognition rather than the horizontal dimension.     

Are the windows to the soul the same in the East and West? Cultural differences in using the eyes and mouth as cues to recognize emotions in Japan and the United States

The current research investigated the hypothesis that, depending on an individual’s cultural background, facial cues in different parts of the face are weighted differently when interpreting emotions. Given that the eyes are more difficult to control than the mouth when people express emotions, we predicted that individuals in cultures where emotional subduction is the norm (such as Japan) would focus more strongly on the eyes than the mouth when interpreting others’ emotions. By contrast, we predicted that people in cultures where overt emotional expression is the norm (such as the US) would tend to interpret emotions based on the position of the mouth, because it is the most expressive part of the face. This hypothesis was confirmed in two studies, one using illustrated faces, and one using edited facial expressions from real people, in which emotional expressions in the eyes and mouth were independently manipulated. Implications for our understanding of cross-cultural psychology, as well of the psychology of emotional interpretation, are discussed.     

Infant interest in their mother's face is associated with maternal psychological health

Early experience can alter infants’ interest in faces in their environment. This study investigated the relationship between maternal psychological health, mother–infant bonding, and infant face interest in a community sample. A visual habituation paradigm was used to independently assess 3.5-month old infants’ attention to a photograph of their mother's face and a stranger's face. In this sample of 54 healthy mother–infant pairs, 57% of mothers (N = 31) reported symptoms of at least one of stress response to trauma, anxiety, or depression. Interest in the mother-face, but not stranger-face, was positively associated with the mother's psychological health. In regression analyses, anxiety and depression predicted 9% of the variance in looking to the mother-face. Anxiety was the only significant predictor within the model. No direct associations were found between mother–infant bonding and infants’ face interest. Taken together, these findings indicate that infant's visual engagement with their mother's face varies with maternal symptoms of emotional distress, even within a community sample.     

Calculating the attentional orientation of an unfamiliar agent in infancy

By the end of the first year, infants are able to recognize both goal-directed and perceptually guided behavior in the actions of non-human agents, even faceless ones. How infants derive the relevant orientation of an unfamiliar agent in the absence of familiar markers such as eyes, ears, or face is unknown. The current studies tested the hypothesis that infants’ calculate an agent's “front” from the geometry of its behavior in the spatial environment. In the first study, 14–15-month-old infants observed a symmetrical, faceless agent either interact contingently with a confederate or act randomly. It then turn toward one of two target objects. Infants were more likely to look in the direction the agent turned than the opposite direction, but only in the contingent condition. In the second study, the location of the confederate and target objects was varied, which in turn influenced which end of the agent infants interpreted as the front. Finally, implications for infants’ early gaze-following behaviors with humans are tested and implications for theory of mind development more broadly are discussed.     

Relations between 18-month-olds’ gaze pattern and target action performance: A deferred imitation study with eye tracking

Deferred imitation studies are used to assess infants’ declarative memory performance. These studies have found that deferred imitation performance improves with age, which is usually attributed to advancing memory capabilities. Imitation studies, however, are also used to assess infants’ action understanding. In this second research program it has been observed that infants around the age of one year imitate selectively, i.e., they imitate certain kinds of target actions and omit others. In contrast to this, two-year-olds usually imitate the model's exact actions. 18-month-olds imitate more exactly than one-year-olds, but more selectively than two-year-olds, a fact which makes this age group especially interesting, since the processes underlying selective vs. exact imitation are largely debated. The question, for example, if selective attention to certain kinds of target actions accounts for preferential imitation of these actions in young infants is still open. Additionally, relations between memory capabilities and selective imitation processes, as well as their role in shaping 18-month-olds’ neither completely selective, nor completely exact imitation have not been thoroughly investigated yet. The present study, therefore, assessed 18-month-olds’ gaze toward two types of actions (functional vs. arbitrary target actions) and the model's face during target action demonstration, as well as infants’ deferred imitation performance. Although infants’ fixation times to functional target actions were not longer than to arbitrary target actions, they imitated the functional target actions more frequently than the arbitrary ones. This suggests that selective imitation does not rely on selective gaze toward functional target actions during the demonstration phase. In addition, a post hoc analysis of interindividual differences suggested that infants’ attention to the model's social-communicative cues might play an important role in exact imitation, meaning the imitation of both functional and arbitrary target actions.     

Do young infants respond socially to human hands?

This study revealed that 4- and 6-month-old infants produced social-communicative behaviours only in response to faces, and not in response to hands. However, infants’ spontaneous responses to hands were unique in that they scanned the space above the hands, perhaps searching for a face.     

Perceptual specialization and configural face processing in infancy

Adults’ face processing expertise includes sensitivity to second-order configural information (spatial relations among features such as distance between eyes). Prior research indicates that infants process this information in female faces. In the current experiments, 9-month-olds discriminated spacing changes in upright human male and monkey faces but not in inverted faces. However, they failed to process matching changes in upright house stimuli. A similar pattern of performance was exhibited by 5-month-olds. Thus, 5- and 9-month-olds exhibited specialization by processing configural information in upright primate faces but not in houses or inverted faces. This finding suggests that, even early in life, infants treat faces in a special manner by responding to changes in configural information more readily in faces than in non-face stimuli. However, previously reported differences in infants’ processing of human versus monkey faces at 9 months of age (but not at younger ages), which have been associated with perceptual narrowing, were not evident in the current study. Thus, perceptual narrowing is not absolute in the sense of loss of the ability to process information from other species’ faces at older ages.     

Individual differences in social, cognitive, and morphological aspects of infant pointing

Little is known about the origins of the pointing gesture. We sought to gain insight into its emergence by investigating individual differences in the pointing of 12-month-old infants in two ways. First, we looked at differences in the communicative and interactional uses of pointing and asked how different hand shapes relate to point frequency, accompanying vocalizations, and mothers’ pointing. Second, we looked at differences in social-cognitive skills of point comprehension and imitation and tested whether these were related to infants’ own pointing. Infants’ and mothers’ spontaneous pointing correlated with one another, as did infants’ point production and comprehension. In particular, infants’ index-finger pointing had a profile different from simple whole-hand pointing. It was more frequent, it was more often accompanied by vocalizations, and it correlated more strongly with comprehension of pointing (especially to occluded referents). We conclude that whole-hand and index-finger pointing differ qualitatively and suggest that it is index-finger pointing that first embodies infants’ understanding of communicative intentions.     

A smile biases the recognition of eye expressions: Configural projection from a salient mouth

A smile is visually highly salient and grabs attention automatically. We investigated how extrafoveally seen smiles influence the viewers' perception of non-happy eyes in a face. A smiling mouth appeared in composite faces with incongruent non-happy (fearful, neutral, etc.) eyes, thus producing blended expressions, or it appeared in intact faces with genuine expressions. Attention to the eye region was spatially cued while foveal vision of the mouth was blocked by gaze-contingent masking. Participants judged whether the eyes were happy or not. Results indicated that the smile biased the evaluation of the eye expression: The same non-happy eyes were more likely to be judged as happy and categorized more slowly as not happy in a face with a smiling mouth than in a face with a non-smiling mouth or with no mouth. This bias occurred when the mouth and the eyes appeared simultaneously and aligned, but also to some extent when they were misaligned and when the mouth appeared after the eyes. We conclude that the highly salient smile projects to other facial regions, thus influencing the perception of the eye expression. Projection serves spatial and temporal integration of face parts and changes.     

Effects of face configuration change on shape perception: a new illusion

We report two experiments indicating that varying the configuration of face features changes perception of an oval aperture windowing the face: as the eyes and mouth of a frontal-view face photograph are moved vertically toward face boundaries, the oval appears increasingly clongated, taller, and narrower; when eyes and mouth are moved toward the nose, the oval appears increasingly rounder, shorter, and wider. This shape illusion is maximised when faces appear upright within the oval and major face features (eyes, nose, and mouth) appear in their correct relative locations. These results establish that processing of a face configuration can affect perception of a geometric shape that shares visual space with a face. Whether the illusion is face-specific or a special case of a more general geometric illusion is discussed.     

Categorization of two-dimensional and three-dimensional stimuli by 18-month-old infants

In two experiments, 18-month-old infants’ categorization of 3D replicas and 2D photographs of the same animals and vehicles were compared to explore infants’ flexibility in categorization across different object representations. Using a sequential touching procedure, infants completed one superordinate and two basic-level categorization tasks with 3D replicas, 2D cut out photographs, or 2D images on photo cubes (“2D cubes”). For superordinate sets, 3D replicas elicited longer mean run lengths than 2D cut outs, and 3D replicas elicited equivalent mean run lengths as 2D cubes. For basic-level sets, infants categorized high-contrast animal sets when presented with 3D replicas, but they failed to categorize any of the 2D photograph sets. Categorization processes appear to differ for 3D and 2D stimuli, and infants’ discovery of object properties over time while manipulating objects may facilitate categorization, as least at the superordinate level. These findings are discussed in the context of infants’ representation abilities and the integration of perception and action.     

Sex, beauty, and the relative luminance of facial features

It has been suggested that the consistent luminance difference between the darker regions of the eyes and mouth and the lighter regions that surround them forms a pattern unique to faces. One of the more consistent uses of cosmetics to make the female face more attractive is to darken the eyes and mouth relative to the surrounding skin. The hypothesis that the size of the luminance difference between the eyes and mouth and the rest of the face affects the attractiveness of male and female faces differently was tested in four experiments in which attractiveness ratings were obtained for images of faces in which the luminance difference between the eyes and mouth and the rest of the face had been manipulated. Female faces were found to be more attractive when this luminance difference was increased than when it was decreased, and the opposite was found for male faces. An interpretation consistent with these results is that the luminance difference between the eyes and mouth and the rest of the face is naturally greater in women than men. In this case increasing or decreasing the luminance difference will make a face more feminine or masculine, respectively, and hence, more or less attractive depending on the sex of the face. Implications for the causes of cosmetics usage are discussed.     

Two are better than one: comparison influences infants' visual recognition memory

Despite a large literature on infants’ memory for visually presented stimuli, the processes underlying visual memory are not well understood. Two studies with 4-month-olds (N = 60) examined the effects of providing opportunities for comparison of items on infants’ memory for those items. Experiment 1 revealed that 4-month-olds failed to show evidence of memory for an item presented during familiarization in a standard task (i.e., when only one item was presented during familiarization). In Experiment 2, infants showed robust memory for one of two different items presented during familiarization. Thus, infants’ memory for the distinctive features of individual items was enhanced when they could compare items.     

Do infants show social preferences for people differing in race?

Do infants develop meaningful social preferences among novel individuals based on their social group membership? If so, do these social preferences depend on familiarity on any dimension, or on a more specific focus on particular kinds of categorical information? The present experiments use methods that have previously demonstrated infants’ social preferences based on language and accent, and test for infants’ and young children’s social preferences based on race. In Experiment 1, 10-month-old infants took toys equally from own- and other-race individuals. In Experiment 2, 2.5-year-old children gave toys equally to own- and other-race individuals. When shown the same stimuli in Experiment 3, 5-year-old children, in contrast, expressed explicit social preferences for own-race individuals. Social preferences based on race therefore emerge between 2.5 and 5 years of age and do not affect social choices in infancy. These data will be discussed in relation to prior research finding that infants’ social preferences do, however, rely on language: a useful predictor of group or coalition membership in both modern times and humans’ evolutionary past.     

Can the eyes reveal a person’s emotions? Biasing role of the mouth expression

In this study we investigated how perception of the eye expression in a face is influenced by the mouth expression, even when only the eyes are directly looked at. The same eyes appeared in a face with either an incongruent smiling, angry, or sad mouth, a congruent mouth, or no mouth. Attention was directed to the eyes by means of cueing and there were no fixations on the mouth. Participants evaluated whether the eyes were happy (or angry, or sad) or not. Results indicated that the smile biased the evaluation of the eyes towards happiness to a greater extent than an angry or a sad mouth did towards anger or sadness. The smiling mouth was also more visually salient than the angry and the sad mouths. We conclude that the role of the eyes as a “window” to a person’s emotional and motivational state is constrained and distorted by the configural projection of an expressive mouth, and that this effect is enhanced by the high visual saliency of the smile.     

Perception of tones by infants learning a non-tone language

This article examines the perception of tones by non-tone-language-learning (non-tone-learning) infants between 5 and 18 months in a study that reveals infants’ initial sensitivity to tonal contrasts, deterioration yet plasticity of tonal sensitivity at the end of the first year, and a perceptual rebound in the second year. Dutch infants in five age groups were tested on their ability to discriminate a tonal contrast of Mandarin Chinese as well as a contracted tonal contrast. Infants are able to discriminate tonal contrasts at 5–6 months, and their tonal sensitivity deteriorates at around 9 months. However, the sensitivity rebound sat 17–18 months. Non-tone-learning infants’ tonal perception is elastic, as is shown by the influence of acoustic salience and distributional learning: (1) a salient contrast may remain discriminable throughout infancy whereas a less salient one does not; (2) a bimodal distribution in tonal exposure increases non-tone-learning infants’ discrimination ability during the trough in sensitivity to tonal contrasts at 11–12 months. These novel findings reveal non-tone-learning infants’ U-shaped pattern in tone perception, and display their perceptual flexibility.     

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.     

Common ground on object use associates with caregivers’ gesturese

Caregivers modify their communication when interacting with infants, and these modifications have been related to children's language development. However, the factors influencing caregivers’ modification of gestures are understudied. This study examined whether infants’ object knowledge, considered as common ground shared with the caregiver, relates to caregivers’ gesturese. Six caregiver-infant dyads were videotaped every two months for 15 min in their homes, from child age 8-to-16 months, while they played with two separate objects (i.e. toys). Results indicated that the changes in infants’ object knowledge were paralleled by associated changes in caregivers’ gestures: parents increased both the amount and the complexity of their gestures.     

A unique look at face processing: the impact of masked faces on the processing of facial features

This experiment utilized a masked priming paradigm to explore the early processes involved in face recognition. The first experiment investigated implicit processing of the eyes and mouth in an upright face, using prime durations of 33 and 50 ms. The results demonstrate implicit processing of both the eyes and mouth, and support the configural processing theory of face processing. The second experiment used the same method with inverted faces and the third experiment was a combination of Experiments 1 and 2. The fourth experiment utilized misaligned faces as the primes. Based on the pattern of results from these experiments, we suggest that, when a face is inverted, the eyes and mouth are initially processed individually and are not linked until a later stage of processing. An upright face is proposed to be processed by analysis of its configuration, whereas an inverted face is initially processed using first-order relational information, and then converted to an upright representation and transferred to face specific regions for configural analysis.     

What do infants see in faces? ERP evidence of different roles of eyes and mouth for face perception in 9‐month‐old infants

The study examined whether face‐specific perceptual brain mechanisms in 9‐month‐old infants are differentially sensitive to changes in individual facial features (eyes versus mouth) and whether sensitivity to such changes is related to infants' social and communicative skills. Infants viewed photographs of a smiling unfamiliar female face. On 30% of the trials, either the eyes or the mouth of that face were replaced by corresponding parts from a different female. Visual event‐related potentials were recorded to examine face‐sensitive brain responses. Results revealed that increased competence in expressive communication and interpersonal relationships was associated with a more mature response to faces, as reflected in a larger occipito‐temporal N290 with shorter latency. Both eye‐ and mouth changes were detected, though infants derived different information from these features. Eye changes had a greater impact on the face perception mechanisms and were not correlated with social or communication development, whereas mouth changes had a minimal impact on face processing but were associated with levels of language and communication understanding. Copyright © 2009 John Wiley & Sons, Ltd.