The effect of music on body-rocking manifested by severely mentally deficient patients in ward environments.

By controlling whether or not music was played in the wards, the effect of music on stereotyped body-rocking was assessed for twelve severely mentally deficient adults who engaged in this behaviour. There were significant differences between male and female patients. While music did not appear to affect rates, but increased the amounts, of body-rocking in both groups, the distribution of this increase was different. These results suggested that the effect of music was to increase the duration of body-rocking sequences. Once the music had been removed there was, for females, a persistence of the increased amount of body-rocking. It was hypothesised that there may be sexual dimorphism in the brain-hemisphere structures which organise rhythmic stimuli.