ABSTRACT.This study extends an operant methodology for the analysis of variables which control aberrant responses displayed by mentally handicapped people. The proportion of time spent in individual, stereotyped topographies by three profoundly mentally handicapped subjects was observed by momentary time‐sampling whilst they were repeatedly exposed to four analogue environments: Alone, Social Disapproval, Academic Demand and Unstructured Play. Two of the three subjects showed replicable effects of the analogue environments. One subject showed evidence of an interaction between stereotyped topography and type of analogue environment. This study shows that the operant methodology of Iwataet al.(1982), originally developed with self injurious responses, can be successfully refined and extended to the analysis of a wider range of aberrant topographie