Lateralization of ERP components during verbal dichotic information processing

Conducted 2 experiments in which Ss were requested to recall dichotic digit pairs. In Exp I, 30 right-handed (RH) undergraduates served as Ss. Recorded spoken digits from 1 to 12 were presented with stereo headphones so that the Ss received 2 digits simultaneously, 1 at each ear. EEGs were done on each S. In Exp II, 24 new RH male students completed only the dichotic task. Results of both experiments show significant right-ear advantage for the digits. In the EEG, a strongly lateralized sustained positive wave was present in the preresponse period. The asymmetry of this component appeared to be both task dependent and related to individual differences in ear asymmetry. It is suggested that the sustained wave is a manifestation of differential mobilization of resources of the 2 hemispheres that compete for limited capacity in a particular stage of the task.