The Cortical Development of Specialized Face Processing in Infancy.

The aim of this study was to examine specialized face processing in forty-eight 4.5- to 7.5-month-old infants by recording event-related potentials (ERPs) in response to faces and toys, and to determine the cortical sources of these signals using realistic, age-appropriate head models. All ERP components (i.e., N290, P400, Nc) showed greater amplitude during periods of attention than inattention. Amplitude was greater to faces than toys during attention at the N290, and greater to toys at the P400. Cortical source analysis revealed activity in occipital-temporal brain areas as the source of the N290, particularly the middle fusiform gyrus. The Nc and P400 were the result of activation in midline frontal and parietal, anterior temporal, and posterior temporal and occipital brain areas.

Infants' perception of emotion from body movements.

Adults recognize emotions conveyed by bodies with comparable accuracy to facial emotions. However, no prior study has explored infants' perception of body emotions. In Experiment 1, 6.5-month-olds (n = 32) preferred happy over neutral actions of actors with covered faces in upright but not inverted silent videos. In Experiment 2, infants (n = 32) matched happy and angry videos to corresponding vocalizations when the videos were upright but not when they were inverted. Experiment 3 (n = 16) demonstrated that infants' performance in Experiment 2 was not driven by information from the covered face and head. Thus, young infants are sensitive to emotions conveyed by bodies and match them to affective vocalizations, indicating sophisticated emotion processing capabilities early in life.

The development of intermodal emotion perception from bodies and voices.

Even in the absence of facial information, adults are able to efficiently extract emotions from bodies and voices. Although prior research indicates that 6.5-month-old infants match emotional body movements to vocalizations, the developmental origins of this function are unknown. Moreover, it is not clear whether infants perceive emotion conveyed in static body postures and match them to vocalizations. In the current experiments, 6.5-month-olds matched happy and angry static body postures to corresponding vocalizations in upright images but not in inverted images. However, 3.5-month-olds failed to match. The younger infants also failed to match when tested with videos of emotional body movements that older infants had previously matched. Thus, whereas 6.5-month-olds process emotional cues from body images and match them to emotional vocalizations, 3.5-month-olds do not exhibit such emotion knowledge. These results indicate developmental changes that lead to sophisticated emotion processing from bodies and voices early in life.

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.

Race-Based Perceptual Asymmetry in Face Processing Is Evident Early in Life.

Adults' processing of own-race faces differs from that of other-race faces. The presence of an "other-race" feature (ORF) has been proposed as a mechanism underlying this specialization. We examined whether this mechanism, which was previously identified in adults and in 9-month-olds, is evident at 3.5 months. Caucasian 3.5-month-olds looked longer at a pattern containing a single Asian face among seven Caucasian faces than at a pattern containing a single Caucasian face among seven Asian faces. Homogenous and inverted face control conditions indicated that infants' preference was not driven by the majority of faces in arrays or by low-level features. Thus, 3.5-month-olds found the presence of an other-race face among own-race faces to be more salient than the reverse configuration. This asymmetry suggests sensitivity to an ORF at 3.5 months. Thus, a key mechanism of race-based processing in adults has an early onset, indicating rapid development of specialization early in life.

Body Representation in the First Year of Life.

Like faces, bodies are significant sources of social information. However, research suggests that infants do not develop body representation (i.e., knowledge about typical human bodies) until the second year of life, although they are sensitive to facial information much earlier. Yet, previous research only examined whether infants are sensitive to the typical arrangement of body parts. We examined whether younger infants have body knowledge of a different kind, namely the relative size of body parts. Five- and 9-month-old infants were tested for their preference between a normal versus a proportionally distorted body. Nine-month-olds exhibited a preference for the normal body when images were presented upright but not when they were inverted. Five-month-olds failed to exhibit a preference in either condition. These results indicate that infants have knowledge about human bodies by the second half of the first year of life. Moreover, given that better performance on upright than on inverted stimuli has been tied to expertise, the fact that older infants exhibited an inversion effect with body images indicates that at least some level of expertise in body processing develops by 9 months of age.

Race-based perceptual asymmetries underlying face processing in infancy.

Adults process other-race faces differently than own-race faces. For instance, a single other-race face in an array of own-race faces attracts Caucasians' attention, but a single own-race face among other-race faces does not. This perceptual asymmetry has been explained by the presence of an other-race feature in other-race faces and its absence in own-race faces; this difference is thought to underlie race-based differences in face processing. We examined the developmental origins of this mechanism in two groups of Caucasian 9-month-olds. Infants in the experimental group exhibited a preference for a pattern containing a single Asian face among seven Caucasian faces over a pattern containing a single Caucasian face among seven Asian faces. This preference was not driven by the majority of elements in the images, because a control group of infants failed to exhibit a preference between homogeneous patterns containing eight Caucasian versus eight Asian faces. The results demonstrate that an other-race face among own-race faces attracts infants' attention but not vice versa. This perceptual asymmetry suggests that the other-race feature is available to Caucasians by 9 months of age, thereby indicating that mechanisms of specialization in face processing originate early in life.

On how patients with multiple sclerosis weigh side effect severity and treatment efficacy when making treatment decisions.

Although effective disease-modifying treatments (DMTs) are available for individuals suffering from multiple sclerosis (MS), many patients fail to take their recommended medications. Unlike medications that provide immediate relief from existing symptoms, DMTs decrease the probability of future symptoms (i.e., a probabilistic benefit) while concurrently carrying an appreciable risk of immediate side effects (i.e., a probabilistic cost). Prior research has shown that both the probability of reducing disease progression and the probability of experiencing side effects impact patients' likelihood of taking a hypothetical DMT. The role that side effect severity plays in treatment decisions remains unexplored. The present study examined how probability of medication efficacy and side effect severity impact patients' likelihood of taking hypothetical DMTs. Patients' likelihood of taking a DMT systematically decreased as medication efficacy decreased and side effect severity increased. Because side effect severity appears to impact decision-making processes in unique ways, the present results suggest that providers should present information on severe (which are typically rare) and mild to moderate side effects (which are more common) separately. (PsycINFO Database Record

The development of sex category representation in infancy: matching of faces and bodies.

Sex is a significant social category, and adults derive information about it from both faces and bodies. Research indicates that young infants process sex category information in faces. However, no prior study has examined whether infants derive sex categories from bodies and match faces and bodies in terms of sex. In the current study, 5-month-olds exhibited a preference between sex congruent (face and body of the same sex) versus sex-incongruent (face and body belonging to different genders) images. In contrast, 3.5-month-olds failed to exhibit a preference. Thus, 5-month-olds process sex information from bodies and match it to facial information. However, younger infants' failure to match suggests that there is a developmental change between 3.5 and 5 months of age in the processing of sex categories. These results indicate that rapid developmental changes lead to fairly sophisticated social information processing quite early in life.

Parts function as perceptual organizational entities in infancy.

Both objects and parts function as organizational entities in adult perception. Prior research has indicated that objects affect organization early in life: Infants grouped elements located within object boundaries and segregated them from those located on different objects. Here, we examined whether parts also induce grouping in infancy. Five- and 6.5-month-olds were habituated to two-part objects containing element pairs. In a subsequent test, infants treated groupings of elements that crossed part boundaries as novel, in comparison with groupings that had shared a common part during habituation. In contrast, the same arrangement of elements failed to elicit evidence of grouping in control conditions in which the elements were not surrounded by closed part boundaries. Thus, infants grouped and segregated elements on the basis of part structure. Part-based processing is a key aspect of many theories of perception. The present research adds to this literature by indicating that parts function as organizational entities early in life.

Parts, cavities, and object representation in infancy.

Part representation is not only critical to object perception but also plays a key role in a number of basic visual cognition functions, such as figure-ground segregation, allocation of attention, and memory for shapes. Yet, virtually nothing is known about the development of part representation. If parts are fundamental components of object shape representation early in life, then the infant visual system should give priority to parts over other aspects of objects. We tested this hypothesis by examining whether part shapes are more salient than cavity shapes to infants. Five-month-olds were habituated to a stimulus that contained a part and a cavity. In a subsequent novelty preference test, 5-month-olds exhibited a preference for the cavity shape, indicating that part shapes were more salient than cavity shapes during habituation. The differential processing of part versus cavity contours in infancy is consistent with theory and empirical findings in the literature on adult figure-ground perception and indicates that basic aspects of part-based object processing are evident early in life.

Transfer of associative grouping to novel perceptual contexts in infancy.

Learning can be highly adaptive if associations learned in one context are generalized to novel contexts. We examined the development of such generalization in infancy in the context of grouping. In Experiment 1, 3- to 4-month-olds and 6- to 7-month-olds were habituated to shapes grouped via the organizational principle of common region and were tested with familiar and novel pairs as determined by the principle of proximity. Older infants generalized from common region to proximity, but younger infants did not. Younger infants failed to generalize when the task was easier (Experiment 2), and their failure was not due to inability to group via proximity (Experiment 3). However, in Experiment 4, even younger infants generalized grouping on the basis of connectedness to proximity. Thus, the ability to transfer learned associations of shapes to novel contexts is evident early in life, although it continues to undergo quantitative change during infancy. Moreover, the operation of this generalization mechanism may be induced by means of bootstrapping onto functional organizational principles, which is consistent with a developmental framework in which core processes scaffold learning.

Part perception in infancy: sensitivity to the short-cut rule.

Research indicates that object perception involves the decomposition of images into parts. A critical principle that governs part decomposition by adults is the short-cut rule, which states that, all else being equal, the visual system parses objects using the shortest possible cuts. We examined whether 6.5-month-olds' parsing of images also follows the short-cut rule. Infants in the experimental conditions were habituated to cross shapes and then tested for their preference between segregated patterns produced using long cuts versus short cuts. Infants in the control conditions were directly tested with the segregated patterns. Infants in the experimental conditions exhibited a greater novelty preference for the long-cut over the short-cut patterns than did those in the control conditions, thereby indicating that they are more likely to segregate cross shapes using short cuts rather than long cuts. This sensitivity to the short-cut rule was evident when two alternative parameters, part area and protrusion, were controlled in Experiments 1 and 2, respectively. Thus, a critical principle that governs part segregation in adulthood is operational by 6.5 months of age.