Does "callosal relay" explain ear advantage in dichotic monitoring?

Abstract

Pairs of consonant-vowel (CV) syllables were dichotically presented to a large sample of healthy subjects (n = 263) who were instructed to monitor for the presence of a target CV (/ta/) which could occur in either ear. The subjects responded by pressing a response button, allowing the recording of reaction times (RTs) and number of correct responses. The investigated sample comprised consistent right-handers (CRH), consistent left-handers (CLH), and mixed-handers (MH). It was found that right-ear targets were detected more frequently and faster than left-ear targets, both in CRH and MH subjects. CLH subjects, on the other hand, responded faster to targets presented to the left ear but there was no ear advantage in terms of the correct responses. The RT data were used to examine whether they are compatible with the callosal relay model of language lateralisation. It was found that the predictions made by the callosal relay model were supported by the RT data for all groups.