After-contraction phenomenon: influences on performance and learning

Three experiments investigated the influence of an after-contraction phenomenon on the performance and learning of a dynamic force-production task. The after-contraction effect refers to an involuntary potentiation (induced by a sustained precontraction) that is thought to summate with voluntary motor commands to bias subsequent responding. The precontraction involved a brief (20 s) static contraction. The subsequent influence of the precontraction on a dynamic force-production task was assessed. Experiments 1 and 2 were aimed at demonstrating the direct impact of the precontraction intensity on the magnitude and decay of the after-contraction effect. The results indicated that as the intensity of the precontraction increased, the magnitude of the induced bias increased. In Experiment 3, the indirect influence on subsequent retention of varying the precontraction intensity during acquisition was investigated. The results indicated that the performance of subjects experiencing varying precontraction intensities during acquisition was inferior to that of subjects experiencing a constant precontraction intensity, but the performance of the varied precontraction intensities group was superior on the test of retention. It is noted that the paradoxical reversal from acquisition to retention is similar to that found in contextual interference experiments and may arise from similar mechanisms.     

Fathers' involvement in their children's healthcare.

Fathers' involvement in the routine healthcare of young children was investigated, and fathers' relative participation in two tasks, staying home with a sick child and taking the child to the doctor or dentist, was assessed. The relationships between fathers' involvement in healthcare and several other measures, including mothers' employment status, fathers' attitudes toward women's rights and roles, the amount of time fathers spent at work, and fathers' involvement in housework, were also examined. The subjects were 50 fathers of young children in intact, White, middle-class families. Both staying home with a sick child and taking a child to the doctor or dentist were usually performed by mothers, but when mothers were employed, fathers were significantly more involved, regardless of the child's sex. Staying home with a sick child and taking a child to the doctor or dentist were positively related to fathers' involvement in housework. Fathers' staying home with a sick child was significantly correlated with fewer hours at work and liberal attitudes toward women's rights and roles; these variables were not related to taking a child to the doctor or dentist. Positive correlations between fathers' involvement in housework and staying home with a sick child and taking a child to the doctor or dentist suggests that fathers' involvement in childcare is viewed as an aspect of family work.     

Overcoming Learned Helplessness: Managerial Strategies for the 1990s

Problems of work force quality in the United States in the 1990s, strategies for managerial response to these problems, and sources of employee resistance to change are discussed.     

Predicting the Everyday Life Events of Older Adults

Predicting the everyday life events of people is a relatively unexplored topic, although several major theoretical approaches deal with related issues. The dispositional approach would assign a causal role to personality, while the situational approach would locate causation in the person's environment. Variations on these two extreme themes invoke an interactionist interpretation. Beyond this, a genuinely transactional approach focuses on the enduring person-environment relationship established as people deal with major and everyday life events. This study investigated a wide range of predictors of daily positive, negative, and ill-health events over time in a sample of 206 older adults. Results showed that personality variables played only a minor role in predicting daily events, although an interaction between extraversion and social network size was significant. Background demographic variables and the major stressors of recent conjugal bereavement and physical disability played a role in daily event occurrences. Overall, the strongest degree of predictability of events came from the events themselves: The high degree of event stability over time indicated the value of a genuinely transactional model in understanding the occurrence of everyday events.     

Dynamic role of social support in the link between chronic stress and psychological distress.

How a chronic environmental stressor can interfere with the buffering effects of social support by eroding social support was analyzed in this prospective, longitudinal study. A classic buffering effect of support was found after 2 months of exposure to the stressor, household crowding. Crowded residents with low perceived support had greater increases in psychological distress than did crowded residents with high perceived support. However, after 8 months exposure the buffering effect disappeared. Moreover, greater crowding had become directly associated with lower support, which in turn was associated with greater increases in psychological distress. All analyses controlled for prior distress. Under some types of chronic stress, the buffering effects of social support may be short-lived because the stressor eventually erodes social support.     

Depression and self-enhancement among Japanese and American students

This study examined the cultural generalizibility of the negative relationship between depression and self-enhancement. Japanese (n = 116) and American (n = 125) students completed the Zung (1965) Self-Rating Depression Scale and three measures of self-enhancement (i.e., the tendency to see oneself in a positive light). As expected, Japanese subjects were found to be more depressed and less self-serving than Americans. Negative correlations between depression and self-enhancement measures were obtained for both samples. Regression analyses of the relationships between measures indicated that sample differences in self-enhancement were explained largely by sample differences in depression. It is proposed that, relative to the Americans, Japanese students had a negative self-schema that led to higher depression and lower self-enhancement.     

Behavioral economics of drug self-administration. II. A unit-price analysis of cigarette smoking.

In behavioral economics, the ratio of response requirement to reinforcer magnitude is referred to as unit price. Previous research with nonhuman subjects has demonstrated that (a) comparable amounts of food are consumed at the same unit price even though different response requirements and reinforcer magnitudes comprise that unit price and (b) increases in unit price decrease food consumption in a positively decelerating fashion. The present study assessed the generality of these findings to the cigarette smoking of 5 human volunteers. During approximately 18 3-hr sessions, various combinations of response requirement (fixed-ratio 200, 400, and 1,600) and reinforcer magnitude (1, 2, and 4 puffs per bout) were arranged. Consumption (i.e., the number of puffs) generally was comparable at the same unit price independent of the response requirement and reinforcer magnitude comprising that unit price. In addition, increasing unit price generally decreased consumption in a positively decelerating fashion. These results extend the generality of the unit-price analysis to human cigarette smoking. Moreover, these results further support the position that reinforcer magnitude and response requirement are functionally equivalent and interact to determine consumption. The concept of unit price, by integrating and summarizing the effects of those two operations, provides a more parsimonious explanation of the results than do separate evaluations of the effects of response requirement and reinforcer magnitude.