Experimental control of rhythm in stereotyped body rocking.

A technique is described which enabled external control of the rhythm of stereotyped body rocking in a profoundly retarded, non-verbal subject. This technique consists of training the individual to synchronize the rhythm of his body rocking with an externally driven pacemaker light. Evidence is presented for experimental control of rhythm in a profoundly retarded, institutionalized child with a chronic history of body rocking.