The psychophysical inquiry into binocular summation

Experiments that compare monocular and binocular visual performance of human psychophysical Os on a variety of visual tasks are reviewed. The review attempts to include all experiments published in English in this century, excluding work on stereopsis, rivalry, and evoked potentials. The concept of probability summation as a baseline for assessing the presence of neural summation is discussed, and the assumptions of several models for estimating probability summation are considered. Experiments are classified in terms of visual task, major categories being increment detection, flicker fusion, brightness magnitude, and contour resolution. A major conclusion is that binocular performance is superior for essentially all task categories and in most cases by a magnitude greater than that predicted by appropriate probability summation models.     

Uncertainty impairs grating detection performance in the cat

Using behavioral techniques, contrast thresholds for detection of grating patterns by the cat were measured under conditions of certainty and uncertainty. For certainty trials, the same combination of spatial and temporal frequencies was presented throughout a test session, whereas with uncertainty, the cat was unable to anticipate which of two spatial (or temporal) frequencies would be presented on a given trial. For most spatiotemporal combinations, uncertainty served to elevate contrast thresholds by almost .3 log units, a finding that parallels the outcome found in human vision. The uncertainty paradigm may provide a useful inferential tool for determining channel bandwidth in cat vision.     

An experimental space combining individual and social performances

This report describes several primate environments in which two or more animals shared a common social area. Automatic programming was used to permit concurrent individual sessions. Some of the behavioral phenomena observed in these environments, including reinforcing properties of social interactions, are discussed.     

Reviews of current books

Pastoral Psychology -     

Similarity of attitudes and constructs in children's friendships

Sex prejudice in children's friendships has frequently been noted. This study examined the role of similarity of attitudes and personal construct ratings in this effect. Subjects were two classes of school children, aged 7–8 and 9–10 years. There were 29 children in each class. Subjects completed an attitude scale, construct rating scale, and sociometric questionnaire. Similarity effects were primarily in the younger children. Boys were more similar to each other in attitudes than were girls, and girls were more similar to each other in construct ratings than were boys (p < .001); there was greater similarity of attitudes and construct ratings in friendship rather than nonfriendship comparison dyads (p < .01). The sociometric data, when compared with sociometric data collected 6 months earlier, showed that these results could not be due to sex differences in the stability of friendships but rather suggested age and sex differences in the informational bases of friendships in middle childhood.     

Perceptual Priming by Invisible Motion

When observers see motion that is not really there, they can nonetheless show evidence of motion priming. And when observers do not see motion that is really there, they also show evidence for motion priming. Evidently, the process responsible for establishing motion correspondence is sensitive to contextual information, and this sensitivity is modulated at preconscious levels of visual analysis.