Patterns of hemispheric perceptual asymmetries: left hemispatial biases predict changes in anxiety and positive affect in undergraduate women

The Intricate Web of Asymmetric Processing of Social Stimuli in Humans

Although the population-level preference for the use of the right hand is the clearest example of behavioral lateralization, it represents only the best-known instance of a variety of functional asymmetries observable in humans. What is interesting is that many of such asymmetries emerge during the processing of social stimuli, as often occurs in the case of human bodies, faces and voices. In the present paper, after reviewing previous literature about human functional asymmetries for social and emotional stimuli, we suggest some possible links among them and stress the necessity of a comprehensive account (in both ontogenetic and phylogenetic terms) for these not yet fully explained phenomena. In particular, we propose that the advantages of lateralization for emotion processing should be considered in light of previous suggestions that (i) functional hemispheric specialization enhances cognitive capacity and efficiency, and (ii) the alignment (at the population level) of the direction of behavioral asymmetries emerges, under social pressures, as an evolutionary stable strategy.

Is low positive emotionality a specific risk factor for depression? A meta-analysis of longitudinal studies

Depression is well known to share a negative cross-sectional relationship with personality constructs defined by positive emotion (positive affect, extraversion, behavioral activation). These Positive Emotionality (PE) constructs have been proposed to represent stable temperamental risk factors for depression, not merely current mood state. These constructs have also been proposed to increase risk specifically for depression, relative to anxiety. We performed a meta-analysis of longitudinal studies to examine the relationship of PE to depression (59 effect sizes) and anxiety (26 effect sizes). In cross-sectional analyses, PE constructs were negatively associated with depression (r = -.34) and anxiety (r = -.24). PE constructs also prospectively predicted depression (r = -.26) and anxiety (r = -.19). These relationships remained statistically significant, but were markedly attenuated, when baseline levels of depression (β = -.08) and anxiety (β = -.06) were controlled. Moreover, depression and anxiety were equally strong predictors of subsequent changes in PE (β = -.07 and -.09, respectively). These findings are consistent with theoretical accounts of low PE as a temperamental vulnerability for depression, but suggest that the prospective relationship of PE to depression may be weaker and less specific than previously assumed. (PsycINFO Database Record

Perceptual asymmetries and handedness: a neglected link?

Healthy individuals tend to weigh in more the left than the right side of visual space in a variety of contexts, ranging from pseudoneglect to perceptual asymmetries for faces. Among the common explanations proposed for the attentional and perceptual advantages of the left visual field, a link with the prevalence of right-handedness in humans has never been suggested, although some evidence seems to converge in favor of a bias of spatial attention toward the region most likely coincident with another person's right hand during a face-to-face interaction. Such a bias might imply an increased efficiency in monitoring both communicative and aggressive acts, the right limb being more used than the left in both types of behavior. Although attentional and perceptual asymmetries could be linked to right-handedness at the level of phylogeny because of the evolutionarily advantage of directing attention toward the region where others' dominant hand usually operates, it is also legitimate to question whether, at the ontogenetic level, frequent exposure to right-handed individuals may foster leftward biases. These views are discussed in the light of extant literature, and a number of tests are proposed in order to assess our hypotheses.

Neuropsychological and interpersonal antecedents of youth depression

This research examined neuropsychological and interpersonal factors that jointly confer vulnerability to youth depression. We proposed that (1) a reduced posterior right hemisphere bias during the processing of facial expressions contributes to subsequent depressive symptoms in youth, and (2) maladaptive responses to interpersonal stress account for this association. Drawing from theory and research indicating sex differences in rates of hemispheric development, we also investigated sex differences in the associations among a reduced posterior right hemisphere bias, maladaptive responses to interpersonal stress, and depressive symptoms. Hypotheses were examined in a longitudinal study of 95 4^th - 8^th graders (M age = 12.33, SD = 1.10). Results supported the notion that a reduced posterior right hemisphere bias confers vulnerability to depressive symptoms over time in a sex-specific fashion, and implicate maladaptive stress responses as an explanatory mechanism.

Perceptual asymmetry and youths' responses to stress: Understanding vulnerability to depression

This research examined the hypothesis that reduced posterior right hemisphere activity interferes with the regulation of emotions and behavior in response to stress, creating vulnerability to depression. Consistent with a diathesis-stress model, we predicted that youth with a reduced posterior right hemisphere bias in emotional processing would engage in less adaptive responses to stress, which would be associated with depressive symptoms in those who reported the recent experience of high, but not low, levels of stress. Participants were 510 4^th through 8^th graders who completed the Chimeric Faces Task and measures of responses to stress and depressive symptoms. Results supported the idea that responses to stress account for the association between reduced posterior right hemisphere activity and depressive symptoms in youth who report high, but not low, levels of stress. This study provides insight into one process through which reduced posterior right hemisphere activity may confer vulnerability to depressive symptoms, and implicates responses to stress as a target for intervention.

Effects of motivational cues on perceptual asymmetry: implications for creativity and analytical problem solving

In 4 experiments, participants were led to focus on either the prospect of positive outcomes (approach anticipation) or the prospect of negative outcomes (avoidance anticipation) and were subsequently administered behavioral measures of relative hemispheric activation. It was found that approach, relative to avoidance-related anticipatory states, produced greater relative right (diminished relative left) hemispheric activation. Experiment 3 additionally demonstrated that this pattern of activation was reversed when approach and avoidance states were not merely anticipatory but were also emotionally arousing. Finally, Experiment 4 replicated earlier findings demonstrating an influence of approach and avoidance anticipatory states on creativity and analytical problem solving (R. S. Friedman & J. Forster, 2001, 2003) and provided evidence that such effects are mediated by differences in relative hemispheric activation.

PTSD Arousal and Depression Symptoms Associated With Increased Right-Sided Parietal EEG Asymmetry

Researchers have proposed that depression and particular types of anxiety are associated with unique patterns of regional brain activation. The authors examined the relationship among posttraumatic stress disorder (PTSD), anxiety, and depressive symptoms and frontal, temporal, and parietal EEG alpha asymmetry in female Vietnam War nurse veterans. The results indicate that PTSD arousal symptoms are associated with increased right-sided parietal activation. However, the combination of arousal, depression, and their interaction explain more than twice the variance in parietal asymmetry compared with arousal alone. The results support the contention that the association between anxiety and right-sided posterior activation is specific to the anxious arousal subtype. These findings underscore the importance of isolating, both theoretically and statistically, emotional subcomponents in studies of regional brain activation.

A Test of the Tripartite Model of Depression and Anxiety in Older Adult Psychiatric Outpatients

This study examined the tripartite model of depression and anxiety in 131 psychiatric outpatients, ages 55-87. Confirmatory factor analyses revealed that a 3-factor model provided an adequate fit to the observed data, that the 3-factor model was empirically superior to 1- or 2-factor models, and that the 3-factor structure obtained in the current sample of older adult outpatients converged with that obtained on a separate, younger 'sample. Negative affect was significantly related to depression and anxiety symptoms and syndromes, and positive affect was more highly related to depression than anxiety symptoms and syndromes. Ways for taking into account possible age-associated differences in emotion in older adults and thus improving the conceptual model of anxiety and depression are briefly noted.

Relationship between coping styles and perceptual asymmetry

This study examined the relationship between coping styles and hemispheric asymmetry, on the basis of prior evidence of reduced posterior right hemisphere (RH) activity in depression, and the relationship between ruminative coping and depression. Two samples of undergraduates (N = 170) completed chimeric faces tasks and 2 measures of coping styles, the self-report Responses Styles Questionnaire and a behavioral choice task. In women but not in men, self-reported rumination was associated with a decreased RH bias on the emotion-based chimeric task. In both genders, choosing to engage in an emotional task was associated with increased RH involvement. Results indicate that although brooding and dwelling on the negative may be associated with decreased RH involvement, openness to emotion may be associated with increased RH involvement.