Links between physical fitness and cardiovascular reactivity and recovery to psychological stressors: A meta-analysis.

A meta-analysis of published studies with adult human participants was conducted to evaluate whether physical fitness attenuates cardiovascular reactivity and improves recovery from acute psychological stressors. Thirty-three studies met selection criteria; 18 were included in recovery analyses. Effect sizes and moderator influences were calculated by using meta-analysis software. A fixed effects model was fit initially; however, between-studies heterogeneity could not be explained even after inclusion of moderators. Therefore, to account for residual heterogeneity, a random effects model was estimated. Under this model, fit individuals showed significantly attenuated heart rate and systolic blood pressure reactivity and a trend toward attenuated diastolic blood pressure reactivity. Fit individuals also showed faster heart rate recovery, but there were no significant differences in systolic blood pressure or diastolic blood pressure recovery. No significant moderators emerged. Results have important implications for elucidating mechanisms underlying effects of fitness on cardiovascular disease and suggest that fitness may be an important confound in studies of stress reactivity.     

Book reviews

TOATES, F. Animal Behaviour: A Systems Approach. Chichester: John Wiley and Sons. 1980. Pp. 299. Hardback £17. Paper back £6.40 ISBN 0 471 27724.

DICKINSON, A. Contemporary Animal Learning Theory. Cambridge: University Press. 1980. Pp. 177. Hardback £12.50. Paperback £3.95. ISBN 0 521 23469 7.     

Rivals without a cause? Relative performance feedback creates destructive competition despite aligned incentives

Whether people compete or cooperate with each other has consequences for their own performance and that of organizations. To explain why people compete or cooperate, previous research has focused on two main factors: situational outcome structures and personality types. Here, we propose that—above and beyond these two factors—situational cues, such as the format in which people receive feedback, strongly affect whether they act competitively, cooperatively, or individualistically. Results of a laboratory experiment support our theorizing: After receiving ranking feedback, both students and experienced managers treated group situations with cooperative outcome structures as competitive and were in consequence willing to forgo guaranteed financial gains to pursue a—financially irrelevant—better rank. Conversely, in dilemma situations, feedback based on the joint group outcome led to more cooperation than ranking feedback. Our study contributes to research on competition, cooperation, interdependence theory, forced ranking, and the design of information environments.     

The contribution of personality characteristics to the relationship between social support and perceived physical health

Although a great deal of research has been conducted on the relationship between social support and physical health, the contribution of personality characteristics to this relationship has rarely been assessed. Structural equation modeling was employed to derive and test a model of the direct and indirect relationships between personality characteristics, social network size, the perceived availability of support, socially supportive behaviors, and perceived physical health with a sample of Pennsylvania adults. Significant paths indicate that individuals who perceive themselves as affiliative and as help seekers and help givers report larger social networks, receive more socially supportive behaviors, and perceive that more support is available to them. The perception that support is available shared a direct relationship with perceived physical health. The utility of including multiple measures of social support and personality characteristics related to receiving support in investigations of the relationship between social support and physical health is discussed.     

Syntactic context and lexical access

Recent studies demonstrating that multiple meanings of an ambiguous word are initially accessed even when only one reading is syntactically appropriate with the preceding context can be criticized on at least two grounds. First, many of the syntactic contexts used were not truly restrictive, and, secondly, subjects may not have had time to integrate the context before processing the ambiguous word. In the present study, subjects listened to a sentence ending in an ambiguous word and then made a lexical decision to a target related to either the appropriate or inappropriate reading. Contexts were completely restrictive, and a pause was introduced between the context and the ambiguous word. Multiple access still obtained, providing further support for the claim that lexical access is not guided by syntactic context.