Intermodal Compensatory Effects in a Visual Search Task with Congenitally Deaf Adults

Abstract

In a visual search paradigm we measured the stimulus onset asynchrony (SOA) between a stimulus and a mask that was required to reach 90% correct responses. This procedure has the advantage of taking into account the real processing time and excluding the time for the generation of the motor response. Twelve congenitally deaf adult subjects and twelve normal subjects were given a visual search task for a target letter O among a varying number of distractor letters Q and vice-versa.

In both groups we found the asymmetrical visual search pattern classically observed with parallel processing for the search for the target Q and with serial processing for the search for the target O (Treisman, 1985 Computer Vision, Graphics, and Image Processing 31 156 – 177). The difference between the mean search slopes for an O target was not statistically significant between the groups; this might be due to the variability within the groups. The visual search amidst the congenitally deaf does not seem to benefit from a compensatory effect in relation to the acoustic deprivation. Our results seem to confirm data reported by Neville (1990 Annals of the New York Academy of Science 71 – 91) obtained by an electrophysiological technique based on event-related potentials. Nevertheless, the deaf subjects were 2.5 times faster at the visual search task.