Although past experience may operate to produce an initial increase in undesired behaviors during behavior modification procedures, the data of the present study demonstrate that these behaviors will decrease if the model is not abandoned at the point when the behavior appears to be getting worse rather than better. (Authors)

Shows that subjects who receive the impression that psychology experiments are worthless exert less time and effort in task performance than subjects who believe in favorable comments, although both groups indicate similar amounts of effort on self-rating scales. Bibliography and table. (RW)