Error patterns in a chord keyboard response task

Errors in a serial choice-reaction time experiment employing two-finger chord responses to alphabetic stimuli are shown to be distributed in a significantly non-random fashion. Two factors are postulated which are relevant to prediction of the error response. These are the presence or absence of a common finger, and the difference in finger separation, between the actual and the required response. It is suggested that the chord response is coded in terms of a pattern (the distance between the two response components). Responses which mirror the correct response about the centre of the hand are also shown to be significantly more frequent.     

Sleep and overextinction of the GSR component of the orienting response

Overextinction of the GSR component of the orienting response was examined in a sample of 68 socially disturbed adolescents. Continued stimulus repetition beyond the point of habituation resulted in GSR return after 50–60 stimulus presentations. However, division of Ss into sleep and non-sleep groups using behavioral and self-report criteria, failed to support Sokolov’s (1963) notion that overextinction is accompanied by drowsiness. A possible explanation of these results is discussed.     

Mediating interpersonal expectancies via vocal cues: Differential speech intensity as a means of social influence

Differential vocal emphasis in the tape-recorded instruction reading for a standard person perception task was manipulated by mechanically raising or lowering the volume of the key words describing the success or failure response alternatives on the rating scale. In a series of three experiments, Ss exposed to success emphasis in the instructions rated the stimulus persons as more successful than did Ss exposed to failure emphasis. This trend was reversed for Ss who listened twice to the instructions. None of the Ss reported awareness of the influence attempt.     

An experimental test of Jameson and Hurvich’s theory of brightness contrast1

Two hundred and fifty-two brightness functions for seven simultaneously presented black, gray, and white squares on black, gray, and white backgrounds approximated power curves with positive exponents when illuminance was varied in seven steps over 1.9 log fL. Mean exponents were significantly larger for whiter vs blacker squares and for squares on the white vs the gray background. Mean exponents also increased more for squares on white than on black or gray backgrounds. Finally, a white replacing a black background elicited increasingly larger décrémentai responses as the squares varied from black to white. Jameson and Hurvich’s opponent-process theory, tested by the experiment, was not predictive.     

Functional equivalence between same-different classifications and judged similarity of Markov patterns

This experiment represented an initial at tempt at comparing same-different classifications and similarity judgments of Markov histoforms sampled from three different schema families. A measure of individual stimulus variability was more strongfy related to classification responses than to judged similarity. Dichotomous responses, derived from the similarity data by imposing threshold criteria, were found to be highly similor to real classification responses when the threshold values were estimated directly from the latter; little correspondence, however, was obtained using optimal classification criteria. The results support the notion that somewhat different features are used in making classification responses and similarity judgments, and indicate the need for developing more sensitive tasks involving controlled scanning of pattem information.     

Visual and tactual form discrimination: Psychophysical comparison within and between modalities

Intermodal perceptual equivaience was investigated, using visual and tactual oddity discrimination and cross-modal matching-to-sample tasks. Four groups of Ss were presented with 100 problems made up of randomly derived forms from five levels of sidedness. The same quadratic relationship was observed for all tasks as a function of complexity, with optimal performance at eight sides. Comman information utilization, as indicated by intercorrelations of performance variables and by correlational analyses with differences in form measures, was not as pronounced within side classes. Evidence concerning the nature of pattern-feature usage in discrimination was obtained from graphical analyses.     

Schematic concept formation: Feature measures and constraint redundancy as predictors

Constraint redundancy (R_c) was varied in order to manipulate the statistical structure of sets of patterns. Measures of pattern features and R_c were related to the categorization by Ss who had experienced different types of preexposure to sets of patterns from the same stimulus domain. Both R_c and pattern measures were related to the categories produced by Ss in a schematic-concept-formation (SCF) task.     

On the detectability of straight lines in visual noise: An extension of French’s paradigm into the millisecond domain

We report the results of a study that investigated the effects of four experimental parameters on the tachistoscopic detectability of dotted lines in a noisy background consisting of dynamic patterns of identical dots. Characteristics of the lines that were explored included dot spacing, dot numerosity, and line orientation. Dot spacing was shown to be the most powerful parameter in determining the masking effect: the closer the dots, the more easily the line was detected. Increasing the number of the dots was also effective in increasing the detectability of a line, but only up to a limit of five dots. The orientation of the line, on the other hand, did not alter its detectability. Increasing the density of the visual masking noise monotonically reduced the detectability of the line. These studies are an extension of French’s (1953, 1954) work, differing mainly in the fact that the stimulus material was presented tachistoscopically rather than in a mode that allowed prolonged (up to 5 sec) examination of the figures. Thus, they put the results in a domain in which physiological interpretations may be more critically evaluated. A comparison of the results suggests that essentially the same sorts of cognitive mechanisms are operating in the millisecond domain as in the longer exposures. This suggests that simple neurological models utilizing the concept of feature filters or detectors may be being prematurely applied to relatively complex perceptual processes.