The effect of active stimulation on the cognitive development of profoundly retarded multiply handicapped adults

Abstract

The population of profoundly retarded multiply-handicapped (PRMH) adults is an extremely impaired one for whom recent research in cognitive development might offer some new hope for future success. Cognitive development has been alternately viewed by theorists as static or dynamic, with those who espouse the former belief citing evidence that either heredity or the environment wholly influences this development, while those who emphasize the latter do so based on the observation that individuals and environments interact, leading to overall cognitive change. Piaget, who proposed that an active interplay between the organism and the environment is a prerequisite for cognitive development, set the pace for the latter camp and has been followed and expanded upon by numerous researchers world-wide who have developed interventive approaches to facilitate cognitive development and who have postulated the plasticity of that development in various populations. However, such plasticity in PRMH adults and the specific possible effect of a different methodology, active stimulation, on that cognitive development has not yet been examined. The present study was undertaken to explore the hypotheses that active stimulation would significantly raise (a) mental ages and (b) sensorimotor stages (developmental level of ages 0-2) of PRMH adults from pre- to post-treatment. Ten participants served as their own controls in ten discrete single-participant studies using a quasi-ABAB design involving one baseline session, four active stimulation treatments, two days of natural extinction, and one follow-up session, with all sessions and treatments lasting twenty minutes each. Participants were assessed on two measures of cognitive development, the Slosson Intelligence Test and the Uzgiris-Hunt Ordinal Scales of Psychological Development to obtain pre-baseline, post-treatment, and follow-up levels, with treatment consisting of a participant's activating a switch (manipulanda) which operated a reinforcing audio-visual stimulus (music box TV) that played for a predetermined duration of 10 seconds per activation. Automated devices controlled reinforcement duration and recorded response frequencies (number of switch activations). Results included significant increases in MA and sensorimotor stages, confirming the hypotheses. These and other data suggested the plasticity of cognitive development in PRMH adults. Related findings, implications, and limitations were also discussed, as were suggestions for future study.