Suprathreshold binocular interactions for grating patterns

Binocular interactions of suprathreshold grating patterns have been investigated using a reaction time measure of contrast detection. Simple reaction times were determined for monocular and binocular viewing conditions over a contrast range from .63 to near threshold. The results from all subjects showed binocular summation for contrast levels near threshold, but there was considerable variation across subjects for contrast levels above threshold. Some subjects showed summation over the entire contrast range, but other subjects showed either binocular inhibition or binocular facilitation for some range of contrast levels. The pattern of binocular interaction for a given subject was consistent for several spatial frequencies. The differences in types of interaction between subjects, the variation in magnitude of binocular interaction with contrast level for each subject, and the data from experiments involving stimulation of noncorresponding retinal areas show that the binocular interactions found for suprathreshold stimuli cannot be accounted for on the basis of probability, and must, therefore, result from physiological interactions between the two eyes. These interactions have been investigated further under conditions of (1) induced fixation disparity, (2) horizontal gratings, and (3) orthogonally oriented gratings.     

Perceptual deprivation,extraversion—introversion and the autokinetic phenomenon

The present study examines the relationships between perceptual-deprivation tolerance and three variables: extraversion, the autokinetic (AK) phenomenon and field-dependence. In addition, the relationship between extraversion and autokinesis (AK) was investigated. Thirty-three male subjects were subjected to 3 hr of perceptual deprivation and, in addition, their scores on each of the three independent variables were obtained. It was found, as hypothesized, that perceptual-deprivation tolerance was negatively related to extraversion and positively related to the intensity of the AK effect. Field-dependence was not related to perceptual-deprivation tolerance. The correlation between extraversion and the autokinetic effect was significant but moderate. The nature of the relationship between these two variables is discussed.     

The relationship between the probability assessor and the outcomes of an event as a determiner of subjective probability

Two experiments were conducted in which 58 subjects assessed the probability of occurrence of positive and negative events. Two types of probabilities were assessed. The first was the probability that an event would occur, influencing the assessor him/herself (SPE). The second was the probability that the same event would occur to someone else, not influencing the assessor (SNPE). Six patterns of assessments were observed. Most of the subjects assessed SPE to be higher than SNPE for positive events and SNPE to be higher than SPE for negative events. In the first experiment SNPE was assessed in regard to someone very close and similar to the assessor while in the second experiment SNPE was assessed in regard to a less-defined “else”. In the latter case the differences between SPE and SNPE were more prominent than in the first. The explanation was given in terms of motivational factors and the availability heuristic.     

Making choice a routine part of mealtimes for persons with profound mental retardation

Despite increased recognition of the importance of providing routine choice opportunities for persons with severe handicaps, this population continues to experience a typical lack of such opportunities. We evaluated a program for increasing the amount of choices made during routine mealtimes by persons with profound mental retardation and minimal communication skills. The choice provision program, involving systematic presentation of alternative food and drink items in a step-wise fashion during the course of the meal, was implemented with three persons in a residential facility. Results indicated that after implementation of the choice program, all three participants made consistently more choices concerning the foods and beverages they consumed relative to baseline. The choice provision program was conducted without extending the amount of time typically allotted to mealtime within the residential setting. Results are discussed in regard to additional research needed to continue developing means of assisting persons with profound mental retardation to exert control over meaningful events in their lives.