Brief maternal interaction increases number, amplitude, and bout size of isolation-induced ultrasonic vocalizations in infant rats (Rattus norvegicus)

The number, amplitude, duration, and bout structure of isolation-induced ultrasonic vocalization (USV) of infant rats (Rattus norvegicus) were measured on postnatal Day 10. Measurements were made before and after a brief, 1-min, active interaction with their mother or before and after a "pick-up" control procedure. Consistent with prior studies, the number of USVs emitted was significantly increased in the period following the maternal reunion but not after the control procedure. The average amplitude of USVs was also greater following maternal reunion. Finally, analyses characterizing the bout structure of USV production indicated that the average bout size (i.e. number of USVs/bout) was increased severalfold following the reunion with the mother, accounting for the greater rate of USV production during the second isolation period.     

Multimodal classical conditioning of fear: contributions of direct, observational, and verbal experiences to current fears

The authors propose that a multimodal classical conditioning model be considered when clinicians or clinical researchers study the etiology of fears and anxieties learned by human beings. They argue that fears can be built through the combined effects of direct, observed, and verbally presented classical conditioning trials. Multimodal classical conditioning is offered as an alternative to the three pathways to fear argument prominent in the human fear literature. In contrast to the three pathways position, the authors present theoretical arguments for why "learning by observation" and "learning through the receipt of verbal information" should be considered classical conditioning through observational and verbal modes. The paper includes a demonstration of how data, commonly collected in research on the three pathways to fear, would be studied differently using a multimodal classical conditioning perspective. Finally, the authors discuss implications for assessment, treatment, and prevention of learned fears in humans.     

How are social identities linked to self-conception and intergroup orientation? The moderating effect of implicit theories

Social identity approaches assume that social identification affects both self-conception and intergroup orientation. The authors contend that such social identification effects are accentuated when people hold a fixed view of human character and attribute immutable dispositions to social groups. To these individuals, social identities are immutable, concrete entities capable of guiding self-conception and intergroup orientation. Social identification effects are attenuated when people hold a malleable view of human character and thus do not view social identities as fixed, concrete entities. The authors tested and found support for this contention in three studies that were conducted in the context of the Hong Kong 1997 political transition, and discussed the findings in terms of their implications for self-conceptions and the meaning of social identification.     

Fostering group identification and creativity in diverse groups: the role of individuation and self-verification

A longitudinal study examined the interplay of identity negotiation processes and diversity in small groups of master's of business administration (MBA) students. When perceivers formed relatively positive impressions of other group members, higher diversity predicted more individuation of targets. When perceivers formed relatively neutral impressions of other group members, however, higher diversity predicted less individuation of targets. Individuation at the outset of the semester predicted self-verification effects several weeks later, and self-verification, in turn, predicted group identification and creative task performance. The authors conclude that contrary to self-categorization theory, fostering individuation and self-verification in diverse groups may maximize group identification and productivity.     

Infant lightness perception: do 4-month-old infants follow Wallach's ratio rule?

When adults view a test disk embedded in a higher-luminance surround, the perceived lightness of the disk is largely determined by the surround-to-disk (S/D) luminance ratio (Wallach's ratio rule). Performance of 4-month-old infants tested with a forced-choice novelty-preference technique was consistent with predictions based on Wallach's ratio rule. This result suggests that the ability to extract and maintain information about local luminance ratios is present early in infancy. This ability is likely to contribute to the development of lightness constancy.     

Contemporary longitudinal methods for the study of trauma and posttraumatic stress disorder

Traditional methods for analyzing trends in longitudinal data have typically emphasized average group change over time. In this article, we propose multilevel, regression-based methods for examining inter-individual differences in intra-individual change and apply these methods to research in trauma and posttraumatic stress disorder (PTSD). The outcome or dependent variable of interest is reconceptualized as an index of dynamic change reflecting the trend or trajectory of an individual's PTSD symptom severity scores across time. A basic statistical model is presented, and analyses and findings are demonstrated with an existing database used in previously published studies. The methods offer promise for future study of the natural course of PTSD chronicity or recovery, risk and resilience factors that influence individual growth or decline, and critical timepoints for intervention.     

Genetics of posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is a prevalent anxiety disorder marked by behavioral, physiologic, and hormonal alterations. PTSD is disabling and commonly follows a chronic course. The etiology of PTSD is unknown, although exposure to a traumatic event constitutes a necessary, but not sufficient, factor. A twin study of Vietnam veterans has shown significant genetic contribution to PTSD. The fact that PTSD's underlying genotypic vulnerability is only expressed following trauma exposure limits the usefulness of family-based linkage approaches. In contrast to the other major psychiatric disorders, large studies for the search of underlying genes have not been described in PTSD to date. Complementary approaches for locating involved genes include association-based studies employing case-control or parental genotypes for transmission dysequilibrium analysis and quantitative trait loci studies in animal models. Identification of susceptibility genes will increase our understanding of traumatic stress disorders and help to elucidate their molecular basis. The current review provides an up-to-date outline of progress in the field of PTSD.     

Cognitive-behavioral therapy for social anxiety disorder: supporting evidence and future directions

The present paper examines the role of cognitive-behavioral therapy (CBT) in the treatment of social anxiety disorder (SAD). A cognitive-behavioral model of SAD is first presented. Different modalities of CBT for SAD are then described, including exposure, cognitive restructuring, relaxation training, and social skills training, and evidence supporting their efficacy is reviewed. The comparative and combined impact of CBT and pharmacotherapeutic interventions is also explored. CBT appears to be an efficacious treatment for SAD. However, the overall efficacy CBT may be increased by closer examination of the active ingredients of treatment. Such analyses may also enable more successful integration of the different CBT techniques and of CBT and pharmacotherapy in the treatment of SAD.     

Time scales in motor learning and development

A theoretical framework based on the concepts and tools of nonlinear dynamical systems is advanced to account for both the persistent and transitory changes traditionally shown for the learning and development of motor skills. The multiple time scales of change in task outcome over time are interpreted as originating from the system's trajectory on an evolving attractor landscape. Different bifurcations between attractor organizations and transient phenomena can lead to exponential, power law, or S-shaped learning curves. This unified dynamical account of the functions and time scales in motor learning and development offers several new hypotheses for future research on the nature of change in learning theory.     

Temporal and spatial characteristics of attention to facilitate manual and eye-movement responses

Previous investigation found that the speed of saccadic eye movements is enhanced when a temporal interval (gap) is introduced between the disappearance of a foveal fixation mark and the appearance of a peripheral target (the gap paradigm). Attention was shown to be involved in the gap paradigm. Here, we investigated relevant temporal and spatial characteristics of attention, manipulating central fixation marks and peripheral targets. Results from three experiments indicate that (i) the speed of manual and eye-movement detection is accelerated when a fixation mark changes abruptly (in less than 100 ms) before its termination in the gap paradigm; (ii) the speed is further accelerated when a peripheral target location is pre-cued; (iii) sufficient time for fixation (1000 ms) is necessary for the facilitation. These results suggest that fast and transient attention at the fixation spot facilitates attentional disengagement process that urges a spatial-orienting mechanism. Sustained attention is required in the engagement process during the fixation.