• 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 magnitude 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.
Brady JP, Berson J. Stuttering, Dichotic Listening, and Cerebral Dominance. Arch Gen Psychiatry. 1975;32(11):1449-1452. doi:10.1001/archpsyc.1975.01760290117014