Perception of two-component electrocutaneous stimuli

Abstract

Electrocutaneous stimuli varying in strength (6,8, 10 V) and frequency (9,27,81 HZ) were presented in pairs. Subjects were asked to give a numerical score to represent their perception of overall difference in a pair. To assess their ability to use numbers and their performance on unfamiliar stimuli, no guidance on the nature of the stimuli or the range or scale of the scores was given. Dimensional analysis indicated that perception of differences in one component was influenced by the absolute level of the other component, if this was constant in the pair, or by the difference. Considerable variation among subjects in the nature and extent of this interference effect was observed. Individual differences scaling (INDSCAL) enabled a satisfactory consensus model to be obtained. An empirical relationship expressing the observed twocomponent difference scores in terms of one-component scores was derived. Increasing voltage level diminished perception of frequency difference. Higher frequency levels augmented perception of voltage difference. This relationship is a modification of the combinatorial model proposed by Krantz and Tversky (1975). Individual differences in the combinatorial process are allowed for by application of the subject weightings from the INDSCAL solution.A working mathematical model of the process by which humans combine a number of simultaneously perceived difference components between two stimuli is a necessary precursor to the routine use of sensory panels to evaluate possibly unfamiliar or nonverbalized stimuli. In this paper, we report the use of electrocutaneous stimuli that vary in both pulsed repetition frequency and voltage to provide a data base for the investigation and model building of the process by which subjects organize and compare multidimensional stimuli.Recent studies suggest that the perception of such stimuli may be characterized as one of three behavior modes. If the components of a stimulus are completely analyzable (discrete psychological dimensions), subjects are able to attend to each component separately. The perceived difference between any two stimuli will thus approximate the sum of the differences perceived along each dimension. At the opposite extreme, the stimulus components may be completely nonanalyzable (interactive) and differences between stimuli are perceived along a single complex dimension. The third behavioral mode is characterized by the perception of both discrete and interactive stimulus components.When comparing pairs of multicomponent stimuli from within a given stimulus set, all three behavioral

Contours of equal perceived amplitude and equal perceived frequency for electrocutaneous stimuli

“…C. L. Van Doren is affiliated with the Departments of Orthopedics and Biomedical Engineering at Case Western. Correspondence may be addressed to him at Rehabilitation Engineering, MetroHealth Medical Center, 2500 MetroHealth Dr., Cleveland, Ohio 44109-1998 (e-mail: clv2@po.cwru.edu). differences in amplitude (MacFie & Thomson, 1981). Cognitive interactions are manifest as changes in cognitive processing time when the subject is asked to attend to only one dimension while another dimension is changing (Garner, 1974;Garner & Felfoldy, 1970).…”