Spontaneously hypertensive Wistar-derived male rats are more aggressive than those of their normotensive progenitor strain

We compared a group of spontaneously hypertensive rats (SHRs) to a group of Wistar-Kyoto (WKY) rats on each of the three most commonly studied forms of aggressive behavior in rats: muricide, intraspecific aggression, and shock-induced fighting (SIF). A significantly higher proportion of SHRs were muricidal; they also fought more at the lowest shock level. A trend for a higher incidence of intraspecific offense behaviors by SHRs was not significant. SHR flinch and jump thresholds were lower than the respective WKY thresholds. Although there were no significant correlations between shock thresholds and any aspects of SIF, the possibility that strain differences in shock sensitivity may contribute to differences in SIF cannot be ruled out. Within strains, there were no correlations among the different forms of aggression. Several different inherited characteristics may be associated with the accentuation of different forms of aggression in SHRs.     

Parallel Neural Systems for Classical Conditioning: Support From Computational Modeling

Classical conditioning has been explained by two main types of theories that postulate different learning mechanisms. Rescorla and Wagner (1972) put forth a theory in which conditioning is based on the ability of the US to drive learning through error correction. Alternatively, Mackintosh (1973) put forth a theory in which the ability of the CS to be associated with the unconditioned stimulus is modulated. We have proposed a reconciliation of these two mechanisms as working in parallel within different neural systems: a cerebellar system for US modulation and a hippocampal system for CS modulation. We developed a computational model of cerebellar function in eyeblink conditioning based on the error correction mechanism of the Rescorla-Wagner rule in which learning-related activity from the cerebellum inhibits the inferior olive, which is the US input pathway to the cerebellum (Gluck et al., 1994). We developed a computational model of the hippocampal region that forms altered representations of conditioned stimuli based on their behavioral outcomes (Gluck & Myers, 1993; Myers et al., 1995). Overall, computational modeling and empirical findings support the idea that, at least in the case of eyeblink conditioning, there may be two different neural systems: the cerebellum which mediates US-based error correction and hippocampus which alters representations of CSs.     

Attempts to Improve Children's Identifications From Sequential-Presentation Lineups

The effectiveness of practice and stringent lineup instructions in improving children's identifications from sequential-presentation lineups was investigated. Elementary school children ( N = 144) viewed a slide sequence of a crime followed by practice or control procedures. In the practice conditions, children either practiced themselves (self) or watched a videotape of a child practicing (modeled). Practice consisted of 2 target-absent lineups (unmixed) or a target-absent lineup and a target-present lineup (mixed) of female photos unrelated to the crime. The control conditions did not engage in identification practice. All witnesses were given stringent instructions for identifying the criminal from target-present or target-absent sequential-presentation lineups. Multiple responding was dramatically reduced. Practice affected gender differentially. Female children increased in correct identifications, whereas male children increased in false rejections. None of the practice procedures reduced foil identifications from target-absent lineups.     

Psychosocial predictors of natural killer cell mobilization during marital conflict.

This study examined how specific emotions relate to autonomic nervous and immune system parameters and whether cynical hostility moderates this relationship. Forty-one married couples participated in a 15-min discussion about a marital problem. Observers recorded spouses' emotional expressions during the discussion, and cardiovascular, neuroendocrine, and immunologic parameters were assessed throughout the laboratory session. Among men high in cynical hostility, anger displayed during the conflict was associated with greater elevations in systolic and diastolic blood pressure, cortisol, and increases in natural killer cell numbers and cytotoxicity. Among men low in cynical hostility, anger was associated with smaller increases in heart rate and natural killer cell cytotoxicity. These findings suggest that models describing the impact of stress on physiology should be refined to reflect the joint contribution of situational and dispositional variables.     

Latino College Student Adjustment: Does an Increased Presence Offset Minority‐Status and Acculturative Stresses?1

This study examined whether minority‐status stresses and acculturative stresses increase the risk of psychological maladjustment of Latino students at a university where Latinos constitute the largest ethnic group. Participants were 338 Latino (228 Mexican American, 110 Central American) college students who responded to a mailed survey. The results of 2 separate hierarchical regression analyses of psychological distress and well‐being, controlling for demographic (gender, socioeconomic status, and ethnicity). sociocultural (level of acculturation), college role (generic college stresses), and personal (academic self‐confidence) influences provided partial support for our hypothesis and demonstrated the incremental predictive validity of acculturative stresses, but not of minority‐status stresses. Results are discussed in terms of the variety of stresses that Latino college students are likely to experience.     

Repressive coping and the recall of emotional material

Abstract

Individuals who possess a repressive coping style are known to have difficulty in retrieving negative autobiographical memories. We investigated whether these findings were specific to autobiographical memories. After learning a story containing positive and negative information about mothers and fathers, repressors remembered significantly fewer negative phrases than did controls, although there were no differences in the recall of positive material.     

The effects of racial stressors and hostility on cardiovascular reactivity in African American and Caucasian men.

This study examined the effects of race-related stressors and hostility on cardiovascular reactivity in 31 African American and 31 Caucasian men. Participants viewed 3 film excerpts that depicted neutral, anger-provoking (but race-neutral), and racist situations. Participants exhibited significantly greater diastolic blood pressure reactivity to anger-provoking and racist stimuli compared with neutral stimuli. In addition, high hostility was associated with higher recovery systolic and diastolic blood pressure levels after exposure to the films. Although the results failed to confirm previous reports of greater reactivity to racism in African Americans, the findings suggest that diastolic blood pressure levels may remain elevated after exposure to racist stimuli. These results indicate that even indirect exposure to interpersonal conflict elicits significant reactivity, which can persist after exposure to the stressor, especially among high-hostile men.