Seth D. Pollak

Recognizing Emotion in Faces: Developmental Effects of Child Abuse and Neglect

The contributions to the recognition of emotional signals of (a) experience and learning versus (b) internal predispositions are difficult to investigate because children are virtually always exposed to complex emotional experiences from birth. The recognition of emotion among physically abused and physically neglected preschoolers was assessed in order to examine the effects of atypical experience on emotional development. In Experiment 1, children matched a facial expression to an emotional situation. Neglected children had more difficulty discriminating emotional expressions than did control or physically abused children. Physically abused children displayed a response bias for angry facial expressions. In Experiment 2, children rated the similarity of facial expressions. Control children viewed discrete emotions as dissimilar, neglected children saw fewer distinctions between emotions, and physically abused children showed the most variance across emotions. These results suggest that to the extent that childrens experience with the world varies, so too will their interpretation and understanding of emotional signals.

Effects of early experience on children's recognition of facial displays of emotion.

The present research examines visual perception of emotion in both typical and atypical development. To examine the processes by which perceptual mechanisms become attuned to the contingencies of affective signals in the environment, the authors measured the sequential, content-based properties of feature detection in emotion recognition processes. To evaluate the role of experience, they compared typically developing children with physically abused children, who were presumed to have experienced high levels of threat and hostility. As predicted, physically abused children accurately identified facial displays of anger on the basis of less sensory input than did controls, which suggests that physically abused children have facilitated access to representations of anger. The findings are discussed in terms of experiential processes in perceptual learning.

Early experience is associated with the development of categorical representations for facial expressions of emotion

A fundamental issue in human development concerns how the young infants ability to recognize emotional signals is acquired through both biological programming and learning factors. This issue is extremely difficult to investigate because of the variety of sensory experiences to which humans are exposed immediately after birth. We examined the effects of emotional experience on emotion recognition by studying abused children, whose experiences violated cultural standards of care. We found that the aberrant social experience of abuse was associated with a change in childrens perceptual preferences and also altered the discriminative abilities that influence how children categorize angry facial expressions. This study suggests that affective experiences can influence perceptual representations of basic emotions.

Selective attention to facial emotion in physically abused children.

The ability to allocate attention to emotional cues in the environment is an important feature of adaptive self-regulation. Existing data suggest that physically abused children overattend to angry expressions, but the attentional mechanisms underlying such behavior are unknown. The authors tested 8-11-year-old physically abused children to determine whether they displayed specific information-processing problems in a selective attention paradigm using emotional faces as cues. Physically abused children demonstrated delayed disengagement when angry faces served as invalid cues. Abused children also demonstrated increased attentional benefits on valid angry trials. Results are discussed in terms of the influence of early adverse experience on childrens selective attention to threat-related signals as a mechanism in the development of psychopathology.

Neurodevelopmental Effects of Early Deprivation in Postinstitutionalized Children.

The neurodevelopmental sequelae of early deprivation were examined by testing (N = 132) 8- and 9-year-old children who had endured prolonged versus brief institutionalized rearing or rearing in the natal family. Behavioral tasks included measures that permit inferences about underlying neural circuitry. Children raised in institutionalized settings showed neuropsychological deficits on tests of visual memory and attention, as well as visually mediated learning and inhibitory control. Yet, these children performed at developmentally appropriate levels on similar tests where auditory processing was also involved and on tests assessing executive processes such as rule acquisition and planning. These findings suggest that specific aspects of brain-behavioral circuitry may be particularly vulnerable to postnatal experience.

Early Stress Is Associated with Alterations in the Orbitofrontal Cortex: A Tensor-Based Morphometry Investigation of Brain Structure and Behavioral Risk

Individuals who experience early adversity, such as child maltreatment, are at heightened risk for a broad array of social and health difficulties. However, little is known about how this behavioral risk is instantiated in the brain. Here we examine a neurobiological contribution to individual differences in human behavior using methodology appropriate for use with pediatric populations paired with an in-depth measure of social behavior. We show that alterations in the orbitofrontal cortex among individuals who experienced physical abuse are related to social difficulties. These data suggest a biological mechanism linking early social learning to later behavioral outcomes.

P3b reflects maltreated children's reactions to facial displays of emotion

Processing of emotion information by maltreated and control children was assessed with event-related brain potentials (ERPs). Maltreated children, for whom negative facial displays may be especially salient, and demographically comparable peers were tested to increase knowledge of differential processing of emotion information. ERPs were measured while children responded to pictures depicting facial displays of anger, fear, and happiness. Maltreated children showed larger P3b amplitude when angry faces appeared as targets than did control children; the two groups did not differ when targets were either happy or fearful facial expressions or for nontargets of any emotional content. These results indicate that aberrant emotional experiences associated with maltreatment may alter the allocation of attention and sensitivity that children develop to process specific emotion information.

Behavioral Problems After Early Life Stress: Contributions of the Hippocampus and Amygdala

BACKGROUND Early life stress (ELS) can compromise development, with higher amounts of adversity linked to behavioral problems. To understand this linkage, a growing body of research has examined two brain regions involved with socioemotional functioning-amygdala and hippocampus. Yet empirical studies have reported increases, decreases, and no differences within human and nonhuman animal samples exposed to different forms of ELS. This divergence in findings may stem from methodological factors, nonlinear effects of ELS, or both. METHODS We completed rigorous hand-tracing of the amygdala and hippocampus in three samples of children who experienced different forms of ELS (i.e., physical abuse, early neglect, or low socioeconomic status). Interviews were also conducted with children and their parents or guardians to collect data about cumulative life stress. The same data were also collected in a fourth sample of comparison children who had not experienced any of these forms of ELS. RESULTS Smaller amygdala volumes were found for children exposed to these different forms of ELS. Smaller hippocampal volumes were also noted for children who were physically abused or from low socioeconomic status households. Smaller amygdala and hippocampal volumes were also associated with greater cumulative stress exposure and behavioral problems. Hippocampal volumes partially mediated the relationship between ELS and greater behavioral problems. CONCLUSIONS This study suggests ELS may shape the development of brain areas involved with emotion processing and regulation in similar ways. Differences in the amygdala and hippocampus may be a shared diathesis for later negative outcomes related to ELS.

Social vocalizations can release oxytocin in humans.

Vocalizations are important components of social behaviour in many vertebrate species, including our own. Less well-understood are the hormonal mechanisms involved in response to vocal cues, and how these systems may influence the course of behavioural evolution. The neurohormone oxytocin (OT) partly governs a number of biological and social processes critical to fitness, such as attachment between mothers and their young, and suppression of the stress response after contact with trusted conspecfics. Rodent studies suggest that OTs release is contingent upon direct tactile contact with such individuals, but we hypothesized that vocalizations might be capable of producing the same effect. To test our hypothesis, we chose human mother–daughter dyads and applied a social stressor to the children, following which we randomly assigned participants into complete contact, speech-only or no-contact conditions. Children receiving a full complement of comfort including physical, vocal and non-verbal contact showed the highest levels of OT and the swiftest return to baseline of a biological marker of stress (salivary cortisol), but a strikingly similar hormonal profile emerged in children comforted solely by their mothers voice. Our results suggest that vocalizations may be as important as touch to the neuroendocrine regulation of social bonding in our species.

Physical abuse amplifies attention to threat and increases anxiety in children

Two experiments using event-related potentials (ERPs) examined the extent to which early traumatic experiences affect childrens ability to regulate voluntary and involuntary attention to threat. The authors presented physically abused and nonabused comparison children with conflicting auditory and visual emotion cues, posed by childrens mothers or a stranger, to examine the effect of emotion, modality, and poser familiarity on attention regulation. Relative to controls, abused children overattended to task-relevant visual and auditory anger cues. They also attended more to task-irrelevant auditory anger cues. Furthermore, the degree of attention allocated to threat statistically mediated the relationship between physical abuse and child-reported anxiety. These findings indicate that extreme emotional experiences may promote vulnerability for anxiety by influencing the development of attention regulation abilities.