The effects of duration of stimulation, preferred hand and familial sinistrality in dichotic monitoring.

Ear asymmetries in dichotic monitoring performance were assessed in 105 subjects (77 M, 28 F). A right ear advantage (REA) was found more often in right than mixed or left handed subjects. Similarly, more left than right handers exhibited left (LEA) or no ear advantages. Handedness did not affect the magnitude of asymmetry. Familial sinistrality could only be examined in male left handers, and was found to increase the incidence of REA's. Non familial sinistrals were equally distributed in terms of left, right and no ear advantage. Overall target detection rates decreased and RT increased as dichotic stimulation progressed, but the ear advantage remained constant throughout the duration of stimulation. Responding hand did not interact with ear stimulated. Dichotic monitoring appears to be a useful non-invasive tool for determining hemispheric dominance for speech perception.