Laterally induced impedance effects in vision

A linear integral equation for a system of mutually impeding points is developed and solved explicitly. Particular solutions are shown to be subharmonic functions for a large class of stimuli. Specialized forms of the general equation presented in this paper occur within a number of mathematical models of Mach bands. In addition to these known spatial properties, our results also show that the time course of this basic equation may be useful in developing models of transient neural activity as well as of temporal psychophysical phenomena, such as the Broca-Sulzer effect. Further, a spatial transfer function much like the low-frequency cutoff of empirically derived modulation transfer functions follows directly from our basic integral equation if the additional assumption of spatial homogeneity is imposed.     

Pyramid Power in Career Development

Stewart and Nejedlo discuss the use of the Career Development Pyramid as a model for career development and as a practical aid in career counseling. The model graphically depicts the synergistic relations of career choice factors, life-style, self-concept, and the specific job. The authors discuss the relationship between the quadrihedral model and current career development theories. They suggest applied uses of the pyramid and provide a working plan for copy and use by career development counselors.     

The object-detection effect: configuration enhances perception.

Line drawings used by Weisstein and Harris (1974) are seen as box-like three-dimensional figures if the lines are arranged properly. A flat two-dimensional pattern is seen when these same lines are disarranged. A target line contained within the three-dimensional figure is identified more readily than is the same line contained within a two-dimensional figure. This finding was extended in the present experiments: The three-dimensional stimulus was detected more quickly than the two-dimensional stimulus, under conditions of visual backward masking. Three-dimensional stimuli were also classified more quickly than two-dimensional stimuli. Just as with the face-detection effect and the word-detection effect, object detection can be affected by the form of the visual stimulus.     

WITHDRAWAL OF CHRONIC CHLORPROMAZINE MEDICATION: AN EXPERIMENTAL ANALYSIS

Approximately 50% of all institutionalized, mentally retarded adults receive psychotropic medication to control inappropriate behavior. In this study, behaviors exhibited by five retarded adults were formally observed while they were on and off medication. Each subject had been receiving chlorpromazine for six or more years prior to the start of the study. The drug was withdrawn and readministered using a double-blind B-A-B (drug-placebo-drug) design. Effects were highly individualized. Some desirable behavior emerged when chlorpromazine was discontinued.     

Structural complexity as a determinant of serial pattern learning

A new methodology extends the study of serial pattern learning to nonhuman organisms by constructing patterns using elements that are both familiar and motivationally meaningful to animals. Two experiments examine the ability of rats to anticipate various quantities of food as measured by running times in a runway when the quantities occur in a serial order. In Experiment 1, a serial monotonic pattern (14-7-3-1-0 food pellets) produced more rapid learning and more accurate anticipation of the various quantities (“tracking”) than a serial nonmonotonic pattern (14-1-3-7-0 food pellets), particularly with respect to the final 0-pellet element. In Experiment 2, the same monotonic pattern generated faster learning and more accurate anticipation of pattern elements than a weakly monotonic pattern (14-5-5-1-0 pellets). Associative explanations including simple excitatory or inhibitory effects, temporal anticipation, reinforcement contrast, and the number and discriminability of pairwise associations are not adequate to account for the data. Rather, the formally defined structural complexity of each pattern adequately predicts its relative difficulty.