Variations in size judgements as a function of surface texture

Adult subjects made monocular size judgements in two experiments in which the independent variables of surface texture and restrictions on viewing conditions were manipulated. Texture density gradients of stimulation had a significant influence of size judgements only under the less reduced conditions of observation when subjects could see other textured surfaces beyond the surfaces over which judgements were made. Identical manipulations of surface texture had earlier been found to have a highly significant influence on relative distance judgements (Newman, 1971). The principally negative results were thus taken to imply that subjects extract different information from the texture density gradient when judging size from that extracted when judging relative distance.     

SCV-A general subroutine for the selection of combinations of variables

SCV is a FORTRAN IV subroutine for sequencing combinations of variables. Selection of the combinations can be random with or without replacement and with equal or unequal frequencies of occurrence. Application is illustrated in terms of an interactive process-control experiment, but the subroutine is applicable to any problem requiring the generation of multidimensional sequences or the permutation of a set of numbers.     

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.