Interference with memory for lifted weight

An adaptation-level model for memory was tested by interpolating different weights between the standard and comparison weights. The results suggest that the model should be modified to account for the general tendency to use alternative categories of judgment with equal frequency. In terms of the modified model, memory for the standard shifts toward the value of the interfering stimulus, the magnitude of shift being proportional to the difference between the interfering stimulus and the value the memory would otherwise have had.     

PIGEONS ARE SENSITIVE TO THE SPATIAL ORGANIZATION OF COMPLEX VISUAL STIMULI

Abstract— Two experiments investigated the role of spatial organisation in the discrimination and generalization of complex visual stimuli by pigeons. In Experiment 1, after pigeons had been trained to discriminate line drawings of four objects, they were tested with novel pictures in which the same component parts of the objects were spatially rearranged. The spatially scrambled pictures led to a dramatic drop in recognition accuracy, hut responding remained above chance. In Experiment 2, pigeons reached a high level of discriminative performance when required to choose among four different spatial arrangements of the same object parts. These results confirm Cerella's (1980) conclusion that pigeons discriminate the component parts of complex visual stimuli, but. unless it is assumed that the scrambling deleted or created emergent features, the results disconfirm his conclusion that spatial organization plays no role in pigeons' picture perception.     

Factors Affecting Stayers’ Job Satisfaction in Response to a Coworker Who Departs for a Better Job1

Two studies examined the consequences of turnover, by investigating factors affecting the job satisfaction of people who remain (i. e., stayers) in response to a coworker (i. e., leaver) who departed for a better job. Consistent with Tesser and Campbell's (1983) self-esteem maintenance model, three factors were found to influence the job satisfaction level of stayers: (a) the extent to which they compared their job situation to the leaver's new one, which was negatively related to stayers’ level of satisfaction, (b) the relevance of the leaver to the stayer for social comparison purposes, which was negatively related to the stayers’ level of satisfaction, and (c) the stayers’ trait self-esteem, which was positively related to the stayers’ level of job satisfaction. Theoretical implications, limitations, and future research directions are discussed.     

The influence of perceptual and motor factors on bimanual coordination in a polyrhythmic tapping task

Summary In this study the role of perceptual and motor factors on the motor organization (integrated versus parallel) adopted by musically skilled and unskilled subjects in a polyrhythmic tapping task was investigated. Subjects tapped a 3:2 polyrhythm to match the timing of two isochronous tone trains, one tone train for each hand. Perceptual factors were examined by the manipulation of the frequency difference between the tone trains to produce either an integrated or a streamed percept. Motor factors were examined by comparison of performance on two versions of the 3:2 polyrhythm. In one (simultaneous) version, each cycle of the polyrhythm began with a simultaneous left- and right-hand tap. In the other (shifted) version a 100-ms interval was introduced between the initial left and right taps in each cycle. Examination of the pattern of variances and covariances among intertap intervals suggested that most of the subjects in this study adopted an integrated motor organization that involved interleaving the timing of the two hands. Further analysis revealed that a serial chained model described the pattern of covariances best for the simultaneous pattern, whereas a hierarchical organization described the pattern of covariances for the shifted pattern best. The finding that performance was more accurate with integrated tones than with streamed tones provides some support for a perceptual-motor facilitation hypothesis.     

Preload and isometric force variability

Two experiments are reported, which examined the relative contributions of preload (resting force level), change of force, and the time taken to achieve the force in determining isometric force variability. The findings showed that change of force is the strongest determiner of peak force variability but that preload and time to peak force have smaller though systematic effects. A formula that predicts peak force variability is proposed, with preload as an additive effect to the ratio between the change of force level and the square root of time to peak force. These findings confirm that these three impulse variables are significant in predicting force variability and that the impact of rate of force on peak force variability is nonlinear.     

A comparison of two multidimensional health locus of control instruments

This study examined the factor structure, internal consistency reliability, and construct validity of the multidimensional health locus of control (MHLC) instruments developed by K.A. Wallston, B.S. Wallston, and DeVellis (1978) and Lau (Lau, 1982; Lau & Ware, 1981). Both measures were administered to a sample of Veterans Administration (VA) medical outpatients (N = 181). Only minimal evidence of convergence was found between corresponding scales of the two MHLC instruments. Low convergent validity appears attributable to the poor internal consistency reliability of the Lau-Ware subscales. Moreover, results of factor analysis largely supported the a priori factor structure of the K.A. Wallston et al. (1978) MHLC instrument but failed to support the factor structure of the Lau-Ware instrument. Health locus of control (HLC) dimensions that emerged from simultaneous factor analysis of both instruments were most consistent with a three-dimensional typology (i.e., Personal Control, Professional Control, and Chance) rather than the four-dimensional typology proposed by Lau (Lau, 1982; Lau & Ware, 1981). Implications for HLC conceptualization and measurement are discussed.     

Stimulus repetition effects and the dimension-feature distinction in alternative targets

The negative repetition effect (NRE) refers to a poorer perception of the target in noise-same-as-target than in noise-alternative-target displays. Using the parenthesis as target and noise that are either identical or different in orientation, we tested predictions derived from a feature-specific inhibition model (Bjork & Murray, 1977) that explains the NRE as arising from inhibitory interactions among channels handling identical inputs. Contrary to our expectation of evidence for orientation-specific inhibition, a positive repetition effect (PRE) was observed. We also found a PRE for the dimension target sets whose stimuli differ only in orientation and an NRE for the feature target sets whose stimuli differ in the number of elements. Further experiments that systematically varied relationships between alternative targets indicate that these basic findings, termed the stimulus attributes effects, do not arise from pattern masking, perceptual strategies, or response bias.     

Performance objectives in the stance phase of human pathological walking

Permanent disruption of aspects of a highly learned skill such as walking force adaptations to occur to the movement. Firstly the body must determine what factors will guide the formation of the new walking pattern, and secondly that new movement pattern must be learned. Frequently the questionable assumption is made that the performance objectives of the new skill are the same as the original. This work used non-linear optimal control and multiple segment simulation to evaluate the ability of several possible objective functions to predict pathological walking patterns. These predictions were then also compared to the results from normal walking. Preliminary results indicate the performance objectives of pathological gaits may be quite different from those of normals. Some support was also provided for the existence of simultaneous multiple performance objectives in complex movements.