Event-related potential correlates of emotion in a dichotic listening task

Auditory and visual modalities have been used to study lateralization of emotional perception. Studies using dichotic stimuli have supported the hypothesis of right-hemisphere dominance for emotional perception, whereas studies of facial emotion perception have provided evidence for the right hemisphere and valence hypotheses. A dichotic target detection task was developed with three aims: (1) acquisition of behavioral and event-related potential (ERP) measures for target emotion identification, (2) determination of the relationship between behavioral and ERP measures, and (3) study of behavioral and ERP effects in homogenous subgroups formed on the basis of ear-advantage and gender. The following predictions for the right hemisphere hypothesis were evaluated: greater accuracy and shorter reaction times for left- than right-ear emotion detection, greater P300 amplitudes over the right than left hemisphere for target stimuli, and an association between P3 amplitude asymmetries and left-ear advantages.;Nonsense syllables stated with seven emotional intonations were dichotically presented to 24 young adults, whose task was to respond to a specified target emotion (happiness, interest, anger or sadness) during four blocks of a dichotic detection task. ERPs were recorded from 14 scalp electrodes with a nose reference. ERP components included N100, a sustained negativity, a late positivity (P3), and a positive going slow wave.;Significantly greater left- than right-ear accuracy was obtained for target emotion identification. Subjects with a strong left-ear advantage (LEA) and women showed a trend for shorter reaction times for targets presented to the left than right ear. Hemispheric asymmetry was found for the N100 and sustained negativity, with greater negativity over the left than right hemisphere, and this asymmetry was largest for right-ear stimuli. The hemispheric asymmetry of N100 and sustained negativity was not significantly correlated with the left-ear advantage and may be related more to early phonetic processing than to emotional perception. Late positivity (P3) and slow wave amplitudes were symmetric and unrelated to behavioral ear advantages. Although, the behavioral data provided evidence for the right hemisphere hypothesis, there was no evidence of an ERP correlate of the behavioral asymmetry for emotional perception.