Developing race categories in infancy via Bayesian face recognition

The other-race effect emerges during infancy following the perceptual narrowing of face recognition. Other-race faces that were previously discriminable in early infancy cannot be distinguished by older infants. I discuss a Bayesian model of this process that posits that the other-race effect may be a consequence of learning to distinguish between intrapersonal variation (changes to face appearance that preserve identity) and extrapersonal variation (changes that do not preserve identity) in a visual environment in which a subset of race categories dominate. I demonstrate that race categories, which I have previously argued are a critical precursor to the emergence of the other-race effect in infancy, are a natural by-product of this model. Perceptual narrowing for race may thus be a natural consequence of visual experience and the estimation of face variability based on a growing number of exemplars. I describe the basic architecture of the model, its applicability to a range of visual learning scenarios, and identify critical choices one faces in applying the model to a specific perceptual task. Despite the success of the model in accounting for these behavioural results, I conclude by identifying important shortcomings of the model and describe important challenges for future efforts to characterize the development of the other-race effect computationally.     

A look at how we look at others: Orientation inversion and photographic negation disrupt the perception of human bodies

Although disproportionate inversion effects have often been considered manifestations of the special processes recruited by upright faces, several papers using sequential matching tasks have reported that body postures also produce sizeable inversion effects. However, comparison of inversion effects observed with transient body postures and effects elicited by judgements of facial structure is complicated by qualitative differences between the stimuli and the tasks. Here we report a series of experiments that use attractiveness judgements to provide a better comparison of the effect of inversion as well as contrast negation on face and body perception. Significant effects of inversion and negation were observed for both face and body stimuli. While the magnitude of the inversion effects was broadly comparable, the negation effect was considerably larger for faces. These effects converge with evidence from cognitive neuroscience to suggest that both faces and bodies recruit similar orientation-specific processes distinct from processes used for generic objects.     

Visual impressions of force exerted by one object on another when the objects do not come into contact

Simple animations in which one object contacts another give rise to visual impressions that the former object causes the outcome for the latter, and that the former object is exerting force on the latter. How does the impression of force relate to the impression of causality? The main aim of this research was to investigate this issue using stimuli in which there is a gap between the objects at closest approach. Delay between the first object stopping and the second object starting to move had a strong effect on reported force impressions, which is consistent with findings of research on the causal impression. However, the reported force impression was little affected by either the size of the gap or the presence and features of an object in the gap, whereas the causal impression was strongly affected by both. The findings support the conclusion that the force impression and the causal impression are distinct components of the visual interpretation of the stimulus.     

A behavioural experiment in virtual reality to verify the role of action function in space coding

Neurophysiological data indicate that the reachable peripersonal space and the unreachable extrapersonal space are represented in segregated parietofrontal circuits and that when the unreachable space becomes reachable because of tool use, it is automatically coded by the network selective for peripersonal space. Here we directly tested the role of action's consequences in space coding. Thirty-eight participants bisected lines at either a reachable distance (60 cm) or unreachable distance (120 cm) using either a laser pointer or laser cutter. The laser cutter but not the laser pointer had an action consequence; the line broke into two pieces. The results showed that distance moderated the effect of action. At an unreachable distance, the mean bisection point was closer to the centre when participants used the laser cutter compared to when they used the laser pointer. There were no differences at a reachable distance (60 cm). This result suggests that the space in which the individual may determine a physical consequence is categorized as peripersonal space, independently from its actual distance from the individual's body.     

Normal face-based judgements of social characteristics despite severely impaired holistic face processing

Initial evidence indicates that face-based judgements of socially relevant characteristics such as people's trustworthiness or attractiveness are linked to the configural/holistic processing of facial cues. What remains a matter of debate, however, is whether such processing is actually necessary for normal social judgements to occur and whether it resembles the type of integrative processing as required for facial identification. To address these issues, we asked a well-characterized case of acquired prosopagnosia (PS) with a marked deficit in holistic processing for face identity to rate a series of faces on several dimensions of social relevance. PS provided ratings within the normal range for most of the social characteristics probed (i.e., aggression, attractiveness, confidence, intelligence, sociability, trustworthiness). Her evaluations deviated from those of healthy controls only when facial dominance was concerned. Taken together, these data demonstrate that the inability to integrate facial information during face individuation does not necessarily translate into a generalized deficit to evaluate faces on social dimensions.     

Us versus them: Understanding the process of race perception with event-related brain potentials

Race is powerful social signal, imbued with a great deal of meaning and capable of affecting a wide range of behaviours and judgements. This review focuses on the use of event-related brain potentials (ERPs) to better understand the process and implications of race perception. Research to date repeatedly demonstrates the speed and automaticity with which racial category membership is encoded. The quick and relatively obligatory encoding of racial ingroup and outgroup distinctions in turn affects a variety of subsequent racially biased behaviours. Such findings not only speak to the close link between social categorization and behaviour, but also have been used to understand how the effects of race perception can be moderated.     

Self-relevance enhances the benefits of attention on perception

ABSTRACT

Considerable efforts have focused on elucidating the influence that self-relevance exerts on perceptual decision-making. To explore this issue further, the current research explored the extent to which stimulus applicability facilitates the benefits of covert attention on early visual processing. In two experiments, we manipulated the personal-relevance of peripheral cues (i.e., geometric shapes) that preceded the appearance of target stimuli (i.e., Gabors) and asked participants to report the orientation of the stimulus with the highest contrast. The results revealed a significant effect of self-relevance on task performance. First, compared to cues associated with a friend or stranger, self-relevant cues enhanced the apparent contrast of a stimulus. Second, the benefits of self-relevance were most pronounced when cues pertained to identities that were significant (vs. trivial or irrelevant) to observers. Together, these findings demonstrate that self-relevance potentiates the benefits of transient attention on stimulus processing.     

Perceptual coupling of multiple point-light figures

When confronted with multiple bistable stimuli at the same time, the visual system tends to generate a common interpretation for all stimuli. We exploit this perceptual-coupling phenomenon to investigate the perception of depth in bistable point-light figures. Observers indicate the global depth orientation of simultaneously presented point-light figures while the similarity between the stimuli is manipulated. In a first experiment, a higher occurrence of coupled percepts is found for identical figures, but coupling breaks down when either the movement pattern or both the viewpoint and the phase-relation are changed. A second experiment confirms these results, but also demonstrates that different point-light actions can be subject to perceptual coupling as long as they share the same viewpoint and exhibit equivalent degrees of perceptual ambiguity. The data are consistent with an explanation in terms of differential contributions of stored, view-dependent object and action representations and of an interaction between stages processing local stimulus features. The consequences of these results are discussed in the framework of an explicit model for the perception of depth in biological motion.     

Are you with me? Probing the human capacity to recognize external/internal attention in others’ faces

ABSTRACT

Facial cues provide information about affective states and the direction of attention that is important for human social interaction. The present study examined how this capacity extends to judging whether attention is internally or externally directed. Participants evaluated a set of videos and images showing the face of people focused externally on a task, or internally while they performed a task in imagination. We found that participants could identify the focus of attention above chance in videos, and to a lesser degree in static images, but only when the eye region was visible. Self-reports further indicated that participants relied particularly on the eye region in their judgements. Interestingly, people engaged in demanding cognitive tasks were more likely judged to be externally focused independent of the actual focus of attention. These findings demonstrate that humans use information from the face and especially from the eyes of others not only to infer external goals or actions, but also to detect when others focus internally on their own thoughts and feelings.     

Size and orientation cue figure-ground segregation in infants

ABSTRACT

Adult perceivers segregate figure from ground based on image cues such as small size and main axis orientation. The current study examined whether infants can use such cues to perceive figure-ground segregation. Three- to 7-month-olds were familiarized with a pie-shaped stimulus in which some pieces formed a?+?and other pieces formed an x. The infants were then presented with a novelty preference test pairing the?+?and x. The bases for the pieces forming the?+?or x were size and orientation (Experiment 1), size (Experiment 2), and orientation (Experiment 3). In each experiment, infants responded as if they recognized as familiar the shape specified by small size, main axis orientation, or their combination. Control conditions showed that infant performance could not be attributed to spontaneous preference. The findings suggest that infants can achieve figure-ground segregation based on some of the same cues used by adults.