Instrumental responding following reinforcer devaluation

In two experiments, hungry rats were given instrumental lever-press training for an appetitive reinforcer and, in addition, were exposed to another type of food which was not contingent on lever pressing. In the first experiment, exposure to each type of food was on separate days, whereas in the second experiment rats were exposed to each type of food in strict alternation within each session. Subsequently, a food aversion was conditioned to the reinforcer for the experimental group and to the non-contingent food for the control group. In both experiments, animals with an aversion to the reinforcer responded less in an extinction test than animals with an aversion to the non-contingent food. Subsequent reacquisition tests confirmed that the aversion to the non-contingent food in the control group was of comparable strength with that to the reinforcer in the experimental group. The results were discussed in terms of whether the reinforcer is encoded in the associative structure set up by exposure to an instrumental contingency.     

Identifying subgroups that succeed or fail with three levels of physical activity intervention: the Activity Counseling Trial.

The authors used recursive partitioning methods to identify combinations of baseline characteristics that predict 2-year physical activity success in each of 3 physical activity interventions delivered in the multisite Activity Counseling Trial. The sample consisted of 874 initially sedentary primary care patients, ages 35-75 years, who were at risk for cardiovascular disease. Predictors of 2-year success were specific to each intervention and represented a range of domains, including physiological, demographic, psychosocial, health-related, and environmental variables. The results indicate how specific patient subgroups (e.g., obese, unfit individuals; high-income individuals in stable health) may respond differently to varying levels and amounts of professional assistance and support. The methods used provide a practical first step toward identifying clinically meaningful patient subgroups for further systematic investigation.     

A method for electronically monitoring the ambulatory activity of honeybees under dark conditions

An electronic apparatus using infrared beams for monitoring the movements of individual bees under dark conditions is described. The searching behavior of workers in an arena was monitored over 2-h periods. Mean ambulatory velocity for one bee over a distance of 100 mm was 45.6±1.51 mm/sec (n=45). Thigmokinesis and temporal activity patterns are illustrated.     

The Role of Status in Producing Depressed Entitlement in Women's and Men's Pay Allocations

Extensive empirical evidence confirms a depressed entitlement effect wherein women pay themselves less than men for comparable work and believe the allocation fair. The present study tests the hypothesis that status subordination linked to being female underlies at least some of this effect. A 2 × 3 design crossed 180 undergraduates' gender with a control condition, which successfully established the depressed entitlement effect, and two experimental conditions. In one, women's status was enhanced through legitimation of women's task abilities; in the other, both women's and men's status was enhanced by adding educational credentials relevant to task ability. Follow-up analyses of the significant interaction revealed that the gap in self-pay demonstrated in the control condition disappeared when women's status was enhanced such that higher-status women's self-pay equaled that of men and exceeded that of control women. Although these findings confirm that status plays a role in producing depressed entitlement in self-pay, ancillary analyses of participants' perceptions point to the persistence of shifting standards and men's resistance to status threats.