ABSTRACT
The idea that mentally retarded persons are inherently more rigid in their behavior than are nonretarded persons has prevailed since the early 1900s. Rigid behavior is stereotyped, perseverative, inflexible, repetitive, and unchanging. Rigid behavior is detrimental to the survival of organisms who need flexible, adaptive behaviors to meet the changing demands of their daily environment. It is this type of behavior that may lead to the inability of mentally retarded persons to function adequately in a normal environment. Various explanations for the causes underlying rigid behavior in mentally retarded persons have been put forth. The initial research on this issue was conducted by Lewin (1935) and Kounin (1941). Although their early work provided the impetus for studying rigidity, it also has been the source of a great deal of confusion and controversy. Much of the later research on rigidity in mentally retarded persons was in reaction to this initial work.
