Stuttering, dichotic listening, and cerebral dominance.

Fully right-sided stutterers (35) and fully right-sided nonstutterers (35) had a dichotic listening task to test hypotheses that stutterers have incomplete cerebral lateralization or reversed lateralization of speech function, or both. An assumption of the procedure is that a right-ear preference indicates left-cerebral dominance for speech. Six stutterers and no nonstutterers showed a reversal, ie, a left-ear preference. As a group, the remaining stutterers who showed no such reversal were the same as nonstutterers in the magnitiude of the right-ear preference. This suggests that a subset of stutterers may have an anomaly in the lateralization of speech functions. A nonsignificant tendency emerged for stutterers to show smaller between-ear differences on the test, consistent with the hypothesis that stutterers have less or incomplete lateralization of speech function than nonstutterers.