Contributions of elicitation to measures of self-control

Pigeons' not pecking or pecking constituted choice between a delayed, large reinforcer and an immediate, small reinforcer (self-control) and at other times between a delayed reinforcer and no reinforcer (omission). Both a tone and a keylight were tested as choice signals, and the delayed reinforcer was either response independent or response dependent. Pigeons pecked during the choice signals on over 95% of the trials in the self-control procedure, and pecked during the choice signals on over 75% of the trials in the omission procedure. Consistent pecking was observed with either the tone or the keylight as a choice signal, with the exception that a tone paired with a response-independent delayed reinforcer did not maintain pecking in the omission procedure. Pigeons pecked during more choice signals when delayed reinforcers were response dependent than when the delayed reinforcers were response independent. These results indicate that Pavlovian conditioning influences self-control experiments, especially in single-key procedures.     

Infant hypotonia, obesity, hypogenitalism and oligophrenia--new viewpoints on the etiology and symptoms of Prader-Willi syndrome

We present four cases of Prader-Willi syndrome. Two of them have an abnormality of a chromosome 15, the other both show different chromosomal abnormalities. Translocations or deletions were found recently in the bands 15q11/12 in about 60% of the cases of Prader-Willi syndrome. The consequences for diagnosis, symptomatology and genetic counselling of the syndrome are discussed.     

Interpersonal attraction,social identification and psychological group formation

Two perspectives on the nature of the social group and psychological group formation are discussed. The traditional social cohesion approach traces group formation to processes of interpersonal attraction, while the social identity approach defines the group in cognitive terms and considers identification, or self-categorization, to be the mechanism of psychological group formation. On the basis of an experiment by Turner, Sachdev and Hogg (1983) it is hypothesized that interpersonal attraction (positive or negative) is related to group formation only in so far as it enhances intergroup distinctiveness. This hypothesis is experimentally tested in a 2 × 3 (interpersonal liking/disliking per se versus no explicit categorization/random categorization/criterial categorization on the basis of affect) factorial design employing the ‘minimal group’ paradigm. People who like each other and were not explicitly categorized formed a group. This effect was enhanced by criterial categorization but disappeared when categorization was random. Although the results do not support the hypothesis, they are not explicable in social cohesion terms. A social identity explanation is furnished—attraction influences group formation by acting, under certain specifiable conditions, as a cognitive criterion for common category membership. This explanation is located in current theorizing and is proposed as part of a reconceptualization of the relationship between interpersonal attraction and group formation.     

Preference for decision structures in a social dilemma situation

Additional results from Rutte and Wilke's (1984) study are presented. In the context of a social dilemma situation two variables were manipulated: use and variance. Preference for various decision structures is the issue of the present paper. It appeared that a large majority structure and an unanimity structure were mast preferred. A small majority structure and a structure in which each decides for him/herself were intermediately preferred. Whereas a structure in which one person, a leader, decides for all was least preferred. Further analysis of these data suggested that only the latter two decision structures were influenced by the use and variance manipulations.     

Estimating social and nonsocial utility functions from ordinal data

This paper reports an experiment testing two hypotheses. The first is that the value or utility associated with a payment to one's self and a payment to a co-worker can be represented as an additive function of a utility for own payment (nonsocial utility) and a utility for the difference between own and other's payment (social utility). The second hypothesis is that changes in the amount of work accomplished by one's self and/or the other should influence the social, but not the the nonsocial utilities. Support for both hypotheses is reported.     

Preschool children's comprehension and production of directive forms

Thirty preschool children, 10 each at the 3-,4-, and 5-year-old levels, participated in two structured tasks designed to assess both comprehension and production of a full range of directive forms. In contrast to previous reports, the results indicated no significant differences in directive comprehension or production as a function of age; children in all age groups demonstrated the ability to understand and verbally encode the intent of most types of directive forms. However, the two most implicit forms, Question Directives and Hints, were complied with significantly less frequently than the more explicit forms, and were uused less often in the production task. The present findings indicate the importance of analyzing directive forms along a continuum of explicitness rather than dichotomizing them as direct versus indirect. Finally, the results are interpreted as providing indirect support for the general notion that mastery of some implicit forms may be achieved later than the acquisition of more explicit forms.