Stimulus and task factors as determinants of ear advantages

Two dichotic experiments are reported which dissociate stimulus and task factors in perceptual lateralization. With only trajectories of fundamental frequency as a distinguishing cue, perception of the voicing of stop consonants gives a right ear advantage. Identification of the emotional tone of a sentence of natural speech gives a left ear advantage. If such parameters as fundamental frequency variation or overall naturalness of the speech material determined the direction of an ear advantage, the reverse pattern of results would have been obtained. Hence the task appears more important than the nature of the stimulus.