Changes of Contingent Negative Variation (Cnv), Visual Evoked Response, and Reaction Time During Repeated Trials in Simple Reaction Time Task

Abstract

The purpose of the present study was to understand both the behavioral (reaction time) and physiological (contingent negative variation and visual evoked response) bases of habituation using a simple reaction time paradigm. Each of 16 adult Ss was given a total of 200 trials with a 1000 msec S1-S2 interval. The results showed that the amplitude of contingent negative variation decreased and reaction time increased over the trial blocks. The visual evoked response, on the other hand, was not changed significantly. The marked habituation effect upon the contingent negative variation was observed in the terminal period of the interstimulus interval. The contingent negative variation (CNV)is classically elicited under the experimental condition us which a warning stimulus (Si) is presented to the S, followed, after a short interval, by an imperative stimulus (Se) to which the S has been instructed to respond. Walter, Cooper, Aldridge, McCallum, and Winter (1964) first reported the existence of the CNV utilizing this model, which is a simple reaction time (RT) paradigm. The CNV has been related to the psychological variables of expectancy, conation, motivation and attention (Tecce, 1972). The evoked response has also been shown to be influenced by psychological factors such as attention directed by counting stimuli and by reaction time task (Kakigi, Miyazaki, & Mori, 1973).There have been few studies, however, investigating the relationship between CNV and evoked response under the condition that CNV and evoked response were monitored separately using the different channels of the amplifier. In most studies, on the other hand, a single channel of long time constant or DC amplifier was used to monitor both CNV and evoked response. By using this measuring method a fast electrical activity such as an evoked response could not be exactly recorded. The present study was, therefore, designed to clarify the relationship between CNV and evoked response using different channels of the amplifier. In addition, habituation of CNV and evoked response, and RT changes during the repeated trials were examined in the present study. The phenomenon of habituation has received much recent attention.