Extraversion and the effects of frequency and intensity on the auditory brainstem evoked response

Extraversion was positively correlated with the latency of wave I of the auditory brainstem evoked response (BER) at 75, 80 and 85 dB of intensity. Extraverts also tended to display longer latency for wave V than introverts to high frequency, 80-dB tone bursts and to click stimuli at intensity levels which ranged from 55 to 85 dB (SPL). These results are consistent with reports of greater auditory sensitivity (d') and enhanced amplitude of the late (N₁–P₂) cortical evoked response for introverts. The absence of differences in interpeak latency, or central transmission time. center the effects on wave I which is thought to be generated by the cochlear nerve. The present findings may require the elaboration of the neurophysiological bases of extraversion, which presently focuses on differences in cortico-reticular arousal systems, to accomodate individual differences in axonal or synaptic transmission.