Simple Reaction Time of Ipsilateral and Contralateral Hand to Monaurally Presented Tones of Different Pitch with Binaural White Noise

Abstract

This study hypothesized that reaction times to monaural auditory stimuli are shorter with the ipsilateral hand than with the contralateral hand under binaural white noise stimulation, and that ipsi- and contralateral reactions do not differ in the absence of white noise. The relationship between the ipsilateral-contralateral reaction time difference and the frequency of the reaction signal was also determined. In experiment I, 10 male undergraduate students each performed 20 ipsilateral and 20 contralateral reactions to each of 6 signal frequencies (400, 800,1200,1600, 2000, 2400 cps) under binaural white noise stimulation. In experiment II, 10 male undergraduate students each performed 20 ipsi- and 20 contralateral reactions, at one stimulus frequency, under white noise on and white noise off conditions. The results support both hypotheses ( p < .001), and also indicate that signal frequency has a significant effect on contralateral reactions· ( p < .001) but not on ipsilateral reactions. Close agreement was obtained with results of other callosal transmission studies, and support provided for the theory that the ear asymmetry effect is caused in part by the occlusion of ipsilateral auditory connections by contralateral ones. The results also suggest that the effect of signal frequency on contralateral reactions is related to the mechanism limiting the frequency at which binaural beats are perceived.