Hypothesizes that behavior changes brought about by oneself will be maintained to a greater degree than behavior changes due to external forces or agents. Within the framework of psychoactive drug therapy, a change in overt behavior which is attributed to one's own efforts should be more persistent than a change in overt behavior which is attributed to a drug. An experimental analogue of drug therapy is reported in which male undergraduate Ss (1) underwent a pain threshold and shock tolerance test, (2) ingested a drug (really a placebo), and (3) repeated the test with the shock intensities surreptitiously halved. All Ss thus believed that a drug had changed their threshold performance. 1/2 of the Ss were then told that they had actually received a placebo, whereas the other 1/2 continued to believe that they had recived a true drug. It was found that Ss who attributed their behavior change to themselves (i.e., who believed they had ingested a placebo) subsequently perceived the shocks as less painful and tolerated significantly more than Ss who attributed their behavior change to the drug. (20 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1969 American Psychological Association.