The present study attempted to determine how a rhythmic beat affects ongoing behavior. A regular stimulus beat was presented to normal subjects who had been instructed to push a bar from side to side. Other subjects had been instructed to emit a vocal response. The individual vocal and motor responses became synchronized with the individual beats of the rhythm. The time between stimulus beats determined the modal interresponse time. These results indicate a synchronization effect: ongoing behavior tends to become synchronized with an ongoing stimulus rhythm. An attempt was made to apply these findings to the problem of stuttering, which can be considered as a disturbance of the natural rhythm of speech. Stutterers were instructed to synchronize their speech with a simple regular beat presented to them tactually by a portable apparatus. The result was a reduction of 90% or more of the stuttering for each subject during the period of synchronization. This effect endured for extended periods of spontaneous speech as well as for reading aloud and was found to be attributable to the rhythmic nature of the stimulus and not to other factors.
EXPERIMENT I: CONTROL OF SIMPLEMOTOR AND VOCAL RESPONSES BY RHYTHM Rhythmic stimuli are believed to exert substantial behavioral influence, as evidenced by the extensive natural use of music. Yet, the basis of this control by music remains unexplained. One known property of music is that when music is contingent upon a response it can be a reinforcer, as shown by Barrett's (1962) punishment of tics by timeout from music and by Ayllon and Azrin's (1965Azrin's ( , 1968aAzrin's ( , 1968b Weidenfeller, 1962Weidenfeller, , 1963Ellis and Brighouse, 1952). Also, the use of music therapy for mental patients seems to be based on the assumption that music affects the general emotional state. Non-contingent music has often been reported as increasing the level of ongoing behaviors, but these reports are often conflicting (see review by Uhrbrock, 1961). Even when a complex musical sound pattern affects ongoing behavior, the question remains as to which aspect of the complex was responsible. The present study attempted a more analytic study of the effect of rhythm by investigating whether a simple regular beat influenced ongoing behavior. The procedure differed from previous studies of rhythm in that the response was a simple and discrete movement of a bar or a simple vocal response, rather than a complex behavioral sequence; similarly, the rhythmic stimulus was a fixed beat rather than a complex musical pattern. The simple nature of the response and the stimulus permitted the evaluation of any point-to-point correspondence in time between them and the eval-283 1968, 1.,283-295 NUMBER 4 (WINTER 1968)