Effects of specific vestibular stimulation and speech therapy on language ability in mentally retarded children were examined. Thirty subjects were assigned to three treatment groups on the basis of the rank order of overall scores on the Porch Index of Communicative Ability in Children (PICAC). Group I received specific vestibular input in addition to specific speech therapy. Group II received specific speech therapy alone. Group III received general speech stimulation. Treatment was given during a 6-week period, Group I receiving semicircular canal stimulation twice a week. Results indicated that all three treatments produce some improvement in general communication skills. Group I showed higher mean percentage gains in all areas of the PICAC, especially verbal, except visual and gestural in which Group II (specific speech) showed highest gains. However, analysis of variance indicated that these differences among groups were not significant.
The hypothetical connection between the vestibular stimulation and language ability or acquisition and implications for future research are discussed.