Contrasting effects of social stress and foot-shock on acute cardiovascular response in salt-sensitive rats

Repeated defeat by an aggressive resident attacker rat produces a large decrement in systolic blood pressure (SBP) in male S/JR rats. The present experiments compared the cardiovascular (CV) response of male S/JR rats exposed either to repeated defeat, or to a common laboratory stressor, electric foot-shock. Using the tail-cuff method of determining SBP, the results of Experiment 1 replicated the previous finding that on the second and subsequent exposures, repeated defeat is followed by an acute decrement in SBP (30-40 mm Hg in magnitude). In contrast, repeated exposures to foot-shock were followed by acute increases in SBP (20-40 mm Hg) and in heart rate (HR). In Experiment 2, mean arterial blood pressure (MAP) and HR were measured directly from chronically cannulated male S/JR rats after defeat or exposure to foot-shock: again, defeated males exhibited an acute decrease in MAP, whereas the MAP of rats exposed to foot-shock tended to increase. In Experiment 3 we varied the parameters of shock intensity and the social context of shock exposure. Male S/JR rats exposed to more intense foot-shock than in the previous experiments or to foot-shock while paired with one of the resident attacker rats all exhibited acute increases in SBP. The results of these experiments indicate that CV response to defeat may be qualitatively different from CV response to foot-shock.     

Leadership ratings for male and female military cadets

Ratings of leadership ability for 1096 male and 91 female cadets at the U.S. Military Academy (West Point) were examined for gender differences. Males were rated significantly higher than females for two of the three rating periods. Correlates of these ratings were examined in an effort to explore the meaning of such ratings for males and females. For both male and female cadets, situationally specific correlates of leadership ratings were identified. Physical ability and performance were most highly correlated with leadership ratings during summer training camp, while academic ability and performance were most highly correlated with these ratings during the academic year. These correlations were generally higher for females than for males. The value of such information to organizational newcomers and the means by which such information might be transmitted to them were discussed.     

Factors in the modification by isolation of electroconvulsive shock-produced retrograde amnesia in the rat.

It has been demonstrated that placing rats in a sensory-restricted environment during the electronconvulsive shock- (ECS) retention interval following 1-trial appetitive learning will prevent or eliminate ECS-produced retrograde amnesia. The first study replicated this finding with a 1-trial aversive learning task, indicating that this effect is not task specific. The second study attempted to determine whether illumination or the restricted environment was the crucial factor in this penomenon. Rats placed in the light during the ECS-retention interval, whether restricted or in the colony, demonstrated retrograde amnesia after ECS. However, rats left in the dark during this interval demonstrated little, if any, retention deficit particularly if this condition was combined with sensory isolation. These studies further indicate that manipulation of the general environment of the animal after ECS can alter ECS-produced retention losses.     

Competitive fighting in the rat.

Competitive fighting was obtained in pairs of like-sexed laboratory rats by placing a single piece of food into the food hopper following 48 hr. of food deprivation. The fighting was characterized by offensive sideways posture, full aggressive posture, and bite and kick attack. Tests were conducted at 110-120 days of age on pairs of animals that had been housed together since weaning. Fighting was more frequent in pairs consisting of nonlittermates than in pairs of littermates, and it was equally frequent in male and female pairings. Probability of fighting was enhanced by prior experience with food deprivation, and attack was most often initiated by the heavier animal of the pair.     

Cognitive processes mediating behavioral change.

The present experiment was designed to test the theory that psychological procedures achieve changes in behavior by altering the level and strength of self-efficacy. In this formulation, perceived self-efficacy. In this formulation, perceived self-efficacy influences level of performance by enhancing intensity and persistence of effort. Adult phobics were administered treatments based upon either performance mastery experiences, vicarious experiences., or they received no treatment. Their efficacy expectations and approach behavior toward threats differing on a similarity dimension were measured before and after treatment. In accord with our prediction, the mastery-based treatment produced higher, stronger, and more generalized expectations of personal efficacy than did the treatment relying solely upon vicarious experiences. Results of a microanalysis further confirm the hypothesized relationship between self-efficacy and behavioral change. Self-efficacy was a uniformly accurate predictor of performance on tasks of varying difficulty with different threats regardless of whether the changes in self-efficacy were produced through enactive mastery or by vicarious experience alone.