Inappropriate speech in a severely retarded child: a case study in language conditioning and generalization.

The modification of inappropriate speech, a class of behaviors rather than a limited number of specific examples, is little known in the severely retarded. In this study, operant techniques were used to modify the strikingly bizarre and inappropriate speech of a severely retarded boy. The boy's appropriate verbal responses to questions about magazine pictures were reinforced with candy. When he responded inappropriately, the magazine was withdrawn, and social interaction was discontinued for a 10-sec timeout period. Negative responses were ignored, the next picture displayed, and the next question asked immediately. In 10 sessions, appropriate responses increased from 26% to 86% of all responses. A reversal of reinforcement was then introduced, in which inappropriate responses were reinforced, appropriate responses resulted in timeout, and negative responses were treated as before. This reduced the percentage of appropriate responses to 24%. Subsequent sessions of reinforcement for appropriate responses increased appropriate responses to 96% of all responses. At significant stages in the experiment, a measure of possible generalization was attempted. Although some generalization was recorded, it was minimal: some explanations are discussed.