Exercise as a buffer of life stress: a prospective study of adolescent health

The hypothesis that physical exercise provides benefits to individuals under periods of life stress has rarely been subject to empirical verification. This article presents the results of a longitudinal study of stress and well-being in adolescence in which the ability of exercise to buffer stress-induced deteriorations in physical health was examined. In accordance with predictions, prospective analyses revealed that the negative impact of stressful life events on health declined as exercise levels increased. These findings suggest that exercise may be a valuable resource for combating life stress. Discussion centers on possible mediating mechanisms and on the practical implications of the results.     

Studies of psychosocial influences on coronary artery atherogenesis in cynomolgus monkeys

The cynomolgus macaque provides a suitable primate model for studying how psychosocial factors contribute to coronary artery atherogenesis. Important interactions with diet, sex, and behaviorally elicited cardiovascular reactivity are described.     

The relationship among genital herpes simplex virus, stress, and social support

Despite widespread popular belief in the activation of recurrent lesions in genital herpes simplex virus (HSV) by psychosocial stress, little empirical evidence supports that contention. This study retrospectively examined the role of stress in activation of HSV lesions as mediated by social support. Participants were 59 volunteers who had self-reported culture-positive genital HSV for at least 10 months. Measures of stress proneness (State-Trait Anxiety Inventory; STAI-Trait), recent stressful events (Schedule of Recent Events; SRE), and subjective appraisal of stress (global self-rating) were administered along with measures of general social support and herpes-specific social support. When retrospective reports of HSV symptoms were examined using a multiple-regression approach, duration of disease and amount of herpes-specific social support were found to be significant moderators of the relation between stress and number of HSV recurrences in the preceding 12 months. When duration of disease was short (less than 4 years), stress (SRE) and number of recurrences were positively associated; when disease duration was longer, there was no relationship. Similarly, at low levels of herpes-specific social support, a positive relation between stress (SRE) and number of recurrences was found. However, at higher levels of herpes-specific social support, no association was found. No relation was found between stress proneness (STAI-Trait) and HSV symptoms. However, subjective appraisal (global rating) of stress in the preceding 12 months was positively and significantly correlated with reported number of recurrences. Results are discussed in terms of their clinical implications.     

Smoking, caffeine, and stress: effects on blood pressure and heart rate in male and female college students

This study examined the independent and joint effects of cigarette smoking and caffeine consumption on blood pressure (BP) and heart rate (HR) reactions to stress in male and female college students. Following an initial physiological baseline, participants received one of four experimental treatments (paced smoking, caffeine, smoking plus caffeine, or neither) and had BP and HR measured before, during, and after two stressful tasks. The results revealed that, compared with the control condition, caffeine ingestion enhanced the magnitude of stress-induced systolic BP and HR reactions. Smoking combined additively with stress, and the joint effect of smoking and caffeine was no greater than either taken alone. Males and females were generally similar in their BP and HR responses to smoking, caffeine, and stress. Inconsistencies with previous research and possible physiological mechanisms underlying the observed effects are discussed.     

Analogical transfer, problem similarity, and expertise

When we encounter a new problem, we are often reminded of similar problems solved earlier and may use the solution procedure from an old problem to solve a new one. Such analogical transfer, however, has been difficult to demonstrate empirically, even within a single experimental session. This article proposes a framework for conceptualizing analogical problem solving that can account for the conflicting findings in the literature. In addition, the framework leads to two predictions concerning the transfer behavior of experts and novices. These predictions concern both positive and negative transfer and are based on the different types of features included in the problem representations of experts and novices. First, when two problems share structural features but not surface features, spontaneous positive transfer should be more likely in experts than in novices. Second, when two problems share surface but not structural features, spontaneous negative transfer should be stronger for novices than for experts. These predictions were supported by the results of three experiments involving college students solving a complex arithmetic word problem.     

Long-term memory in amnesia: cued recall, recognition memory, and confidence ratings

We explored what kind of information is acquired when amnesic patients are able to exhibit significant retention on tests of cued recall and recognition memory. Amnesic patients and control subjects attempted to learn sets of sentences. Memory for the last word in each sentence was tested after 1 hr in the case of the amnesic patients, or after 1 to 2 weeks in the case of (delayed) control subjects. Amnesic patients and (delayed) control subjects performed at similar levels on tests of cued recall and recognition memory. Amnesic patients were just as confident of their correct answers as were control subjects. However, amnesic patients were no more disadvantaged than control subjects when they were cued indirectly by presenting paraphrases of the original sentences. These findings demonstrate that the residual knowledge retained by amnesic patients can be as flexible, as accessible to indirect cues, and as available to awareness as the knowledge retained by (delayed) control subjects.     

Conditioning of appetitive and consummatory sexual behavior in male Japanese quail.

Two different types of stimulus objects, a live female quail artificially adorned with bright orange feathers and an inanimate toy dog, served as conditioned stimuli. For subjects in experimental groups, the conditioned stimuli were presented shortly before access to a sexually receptive normal female quail. For subjects in control groups, exposure to the conditioned stimuli was unpaired with copulatory opportunity. Subjects in the experimental but not in the control groups quickly came to approach the location of the conditioned stimulus objects. When an adorned female quail served as the conditioned stimulus, the conditioned approach behavior was controlled by a combination of the presence of the orange adornments and the visual cues of the head and neck of the female bird, and the approach behavior persisted as the adorned female moved to new locations. When the toy dog served as the conditioned stimulus, the conditioned approach behavior was limited to the spatial cues that surrounded the toy dog during conditioning trials. Although both types of stimulus objects evoked conditioned approach behavior, only the adorned female stimulus supported copulatory behavior. This last finding indicates that copulatory behavior can become redirected toward novel stimuli as a result of conditioning, but only under special circumstances. The results are consistent with the suggestion that appetitive components of reproductive behavior are more susceptible to conditioning than consummatory components. Possible reasons for this are discussed, together with implications of the results for the contribution of conditioning processes to sexual selection.     

A cost-benefit analysis of demand for food.

Laboratory studies of consumer demand theory require assumptions regarding the definition of price in the absence of a medium of exchange (money). In this study we test the proposition that the fundamental dimension of price is a cost-benefit ratio expressed as the effort expended per unit of food value consumed. Using rats as subjects, we tested the generality of this "unit price" concept by varying four dimensions of price: fixed-ratio schedule, number of food pellets per fixed-ratio completion, probability of reinforcement, and response lever weight or effort. Two levels of the last three factors were combined in a 2 x 2 x 2 design giving eight groups. Each group was studied under a series of six FR schedules. Using the nominal values of all factors to determine unit price, we found that grams of food consumed plotted as a function of unit price followed a single demand curve. Similarly, total work output (responses x effort) conformed to a single function when plotted in terms of unit price. These observations provided a template for interpreting the effects of biological factors, such as brain lesions or drugs, that might alter the cost-benefit ratio.