TESTS OF THE “CARPENTERED WORLD” HYPOTHESIS BY RACE AND ENVIRONNEMENT IN AMERICA AND ZAMBIA1

La sensibilité aux illusions optico-géométriques est-elle un trait héréditaire ou dérive-t-elle de facteurs d'environnement ? Ces deux hypothèses — hypothèse physiologique de Pollack et hypothèse écologique de Segall et al. — ont été examinées à l'aide des illusions de Muller-Lyer et de Sander appliquées à un échantillon américain et cinq échantillons zambiens. Dans le premier cas, on a étudié l'effet des variations de pigmentation rétinienne en milieu constant; en Zambie, au contraire, la variable raciale étant contrôlée, on a observé l'influence de différentes écologies (degré de “charpentisation” du milieu). Les résultats ne révèlent aucun effet significatif dû à la pigmentation rétinienne et appuient l'hypothèse de l'influence écologique. l'effet de la variable âge est aussi confirmé, la suggestibilité diminuant avec l'âge, tandis qu'apparaît un effet peu remarqué jusqu'ici, celui du sexe, les femmes se montrant moins sensibles à l'illusion.     

Reducing delusional speech in chronic, paranoid schizophrenics

Four schizophrenic patients with paranoid and grandiose delusions who had been hospitalized for an average of 17 yr were exposed to social reinforcement contingencies in a multiple baseline design. During the baseline period, each patient was interviewed for four 10-min sessions each day. The elapsed time from onset of conversation to onset of delusional talk was recorded. At the end of each day, the patients engaged in a 30-min informal chat with a nurse-therapist while relaxing with coffee, snacks, and cigarettes. The intervention introduced two contingencies: (1) The 10-min interviews were terminated as soon as the patient began talking delusionally; (2) The patients earned time for their evening chat by talking rationally during their daytime interviews. Increases of from 200 to 600% in the amount of rational talk exhibited during the interviews occurred as the contingencies were introduced for each patient sequentially over time. These increases were maintained in three patients when the amount of reinforcement was halved, but declined when the patients were confronted directly with their delusional ideas. A modest amount of generalization occurred from the day-time interviews to the evening chats but did not extend to the behavior of the patients on the ward.     

The effects of music and task difficulty on performance at a visual vigilance task

Forty subjects performed a visual vigilance task in music or noise and when the task was difficult or easy. Response measures taken were: correct detections, commission errors, detection latencies and d' values. For the difficult version of the task a significant increase in detection latencies was found which music prevented. Broadly similar findings were obtained for correct detections. The results are compared with other studies of detection latency and task difficulty and are discussed in terms of arousal.     

Transforming curves into curves with the same shape

Curves are considered to have the same shape when they are related by a similarity transformation of a certain kind. This paper extends earlier work on parallel curves to curves with the same shape. Some examples are given more or less explicitly. A generalization is used to show that the theory is ordinal and to show how the theory may be applied to measure sensation. The problem of actually transforming curves into curves with the same shape is reduced to the problem of rendering another set of curves parallel. Connections with groups and rings are developed to place the work in a familiar context. These connections and the earlier work on parallel curves are used to obtain necessary and sufficient conditions for the existence of transformations, to study the uniqueness of transformations and to show how transformations can be calculated.