Residential density and psychological health: the mediating effects of social support

People report excessive, unwanted social interactions, insufficient privacy, and are observed to be more socially withdrawn under crowded living conditions. If people socially withdraw from one another as a way to cope with crowding, this could lead to an unintended side effect of breakdowns in socially supportive relationships. A breakdown in socially supportive relationships could, in turn, account for some of the pathological consequences of chronic, high density living conditions. An empirical study of 175 male heads of household among inner city residents in India suggests that the adverse effects of residential crowding on psychological health are mediated by a breakdown of social support systems. The study also points to the value of examining social support as an endogenous variable in the stress and health process.     

Cardiovascular reactivity and interpersonal influence: active coping in a social context

Previous studies have demonstrated that effortful attempts to secure positive outcomes or avoid negative outcomes produce significant increases in systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR). Although these effects of active coping on cardiovascular reactivity are central in current psychosomatic theories, virtually all of the research to date has used impersonal, asocial tasks. Our two studies examined the cardiovascular effects of effortful attempts to influence other people. In Study 1, male subjects attempting to influence the opinions of their discussion partner to improve their own chances of winning money displayed significantly greater SBP, DBP, and HR reactivity. In Study 2, we obtained similar effects on SBP and DBP reactivity in men and women, while both preparing an influence attempt and making that attempt. Furthermore, reactivity levels were larger as the magnitude of incentive for successful persuasion increased. Implications of this interpersonal equivalent of active coping for the development of cardiovascular disease are discussed.     

Form and exploration of mechanical stability limits in erect stance

The stability limits of erect stance are described as a geometrical structure in a movement space. Mechanical properties and response latency, a neural property, are determining factors for the stability limits. Standing stability limits of adults and young children are compared, and a simple scheme is suggested by means of which infants can discover the stability limits as they learn to stand. The mechanics of different standing movements are discussed because their spatial temporal properties relate directly to their different stability limits. The combination of the stability limits for different movements gives a total set of stability limits, a different structure for adults than for children.     

The child's perceptions of familial relationships: convergence between two assessment techniques

Children's (N = 28) perceptions of familial relationships were investigated with the Family Environment Scale (FES) and the Network of Relationships Inventory (NRI). The FES assesses overall impressions of the family, and the NRI measures perceptions of individual relationships. Because current family systems theory indicates that positive individual relationships within a dyad (e.g., child-mother) should be related to an overall favorable impression of the family system, we hypothesized that these two instruments should demonstrate convergence on selected dimensions. Results indicated that positive or negative relationships with an individual family member were related to how the child perceived the overall family system, supporting our hypothesis.     

The role of propulsive muscles of the shoulder during quadrupedalism in vervet monkeys (Cercopithecus aethiops): implications for neural control of locomotion in primates

In comparative anatomical studies of the shoulder, the humeral retractors are often grouped together as propulsive muscles, which are important in the propulsive stroke of the forelimb during quadrupedal locomotion. Electromyographic (EMG) analyses of these muscles in opossums, cats, and dogs in general have confirmed such conclusions. An EMG study of chimpanzee shoulder muscles during knuckle-walking found, however, that the humeral retractors are either inactive or perform a function unrelated to propulsion (Larson & Stern, 1987). This contrast in muscle recruitment patterns between chimpanzees and more "typical" mammalian quadrupeds was attributed to the derived morphology of the chimpanzee shoulder. The present study examines the activity patterns of the humeral retractors in the vervet monkey, a primate more closely resembling nonprimate mammals in its shoulder morphology. The results of this EMG analysis show that despite the significant differences in anatomy between chimpanzees and vervets, the two species display very similar muscle recruitment patterns during quadrupedalism, and there is evidence for this same pattern in other species of primates. These differences in muscle activity patterns between primates and nonprimate mammals may be related to changes in the neurological control of locomotion in primates due to the evolutionary development of manipulative abilities in the primate forelimb.     

Is dependence on phonological information in children's reading a product of instructional approach?

Eight-year-old British children were found to be less accurate at rejecting pseudohomophones than ordinary nonwords in a lexical decision task, but 8-year-old New Zealand children did not show this effect. A subsequent homophone decision task showed that this difference was not due to the New Zealand children being unable to distinguish pseudohomophones from other nonwords. The New Zealand children, however, were less accurate than the British children in pronouncing the pseudohomophones they had identified. It was argued that the British children tended to sound out the items before making a choice in the lexical decision task, which gave salience to phonological rather than visual information, resulting in increased errors to the pseudohomophones. It was concluded that where the British children showed this dependency on use of phonological information it was a product of the teaching approach they had experienced.     

Developmental trends in the understanding of perceptual adaptation

In the first of three studies, kindergartners, third graders, and sixth graders were questioned to determine whether they comprehend five types of perceptual adaptation or contrast effects. The results indicated little consistency among kindergartners, but there were strong improvements by the third-grade level, and at the sixth-grade level almost all of the children were showing perfect performance, demonstrating comprehension of the five forms of perceptual adaptation. In the second and third studies, children and adults were placed in a situation in which adaptation to temperature and weight could occur, and they were asked to predict subsequent perceptions. Correct performance in these studies generally occurred at later ages than in Study 1 with even college students showing incorrect performance in some cases. However, the age trends shifted quite markedly depending upon the nature and structure of the task. The results were consistent with a theory stressing the relation of early formed schemas in the form of memory traces of experiences to later appearing and more abstract schemas. The results show the importance of studying older children when considering developing theories of mind.