The Structure of Vocational Interests for Diverse Racial-Ethnic Groups

We investigated differences in the circular structure of Holland's interests types across racial-ethnic groups (African Americans, Mexican Americans, Asian Americans, Native Americans, and Caucasians; N = 11,610). The samples consisted of college-bound persons who completed the revised Unisex Edition of the ACT Interest Inventory (UNIACT; Swaney, 1995), as well as comparison group of 10th graders ( N = 4,133) in the 1992 UNIACT norms sample. Analyses using a randomization test of hypothesized order, targeted principal components, and three-way multidimensional scaling suggest that Holland's model adequately represents the interest structures of both sexes in all the diverse samples.     

A digital system for recording startle,responses in small animals

An easily constructed, isometric startle-recording system is described. The animal enclosure is attached to a plywood board-which, in ten, is mounted in a “springboard” arrangement. Movement is detected by a phonocartridge mounted beneath the chamber, and a digital record of this movement is obtained through the use of a voltage-to-frequency converter. A brief experiment in which the system was used to assess the rat’s reaction to electric footshock is also presented.     

Aftereffect of visual movement: Storage in the absence of a patterned surround

Storage of the visual movement aftereffect is shown to occur if, after movement, the stationary target remains clearly visible in a surround that is dark and featureless. This finding is considered in terms of the earlier observation that the movement aftereffect is reduced or eliminated when the target surround is featureless. It is noted that current hypotheses in terms of direction-specific units cannot easily explain the storage of the movement aftereffect.     

Systematic reinforcement: academic performance of underachieving students

The effect of contingent tangible and social reinforcement on academic performance was investigated in an experimental classroom of 25 selected underachieving students. Measures were taken of both teacher and child behavior during a baseline and two experimental treatment periods. During Treatment I, a point system with tangible backup reinforcers was combined with contingent social reinforcers dispensed by the teaching staff to assess the effects on three measures of academic performance (i.e., per cent of time at work, work output per minute, and accuracy). During Treatment II, the contingencies for the tangible reinforcers were terminated while social reinforcement was continued to see if the positive effects of Treatment I on academic performance would persist. The results show that with combined tangible and social reinforcers, students' work time, rate of output per hour, and accuracy in all activities substantially increased. After termination of the tangible reinforcers, the students maintained their high rates of output per hour and accuracy for the remaining period of the study while the total amount of time at work returned to the baseline level.     

Practice,refractive error,and feedback as factors influencing peripheral motion thresholds

Motion thresholds were determined in the fovea and in the horizontal peripheral meridian under conditions of practice, correction of refractive error, and feedback. While foveal determinations did not change significantly, peripheral motion thresholds were lowered for all conditions. Both practice and practice with feedback produced significantly better motion discrimination, these effects showing a longevity of several months. However, the largest improvement resulted from correction of peripheral refractive error, which also reduced individual differences. This suggests that peripheral sensitivity to movement is ordinarily limited primarily by dioptric rather than neural factors. Implications for perceptual learning and peripheral vision research are discussed.     

The effect on a difficult co-ordination task of the frequency of signals

Subjects were required to direct, by moving hand and foot controls, a fugitive spot of light into one of four positions in accordance with changes in the source of signals, and simultaneously, to extinguish two lights using a left-hand response. Two groups of subjects have been tested on this complex co-ordination task. Increasing the frequency of the signals from four successively but irregularly functioning sources was found to increase significantly the “error” scores in controlling the fugitive spot. Variations in signal frequency did not affect the other part of the task requiring left hand responses to a different set of signals. The order of a sequence of 4-signal frequencies over four trials had no effect on the efficiency with which the task was performed.