Self-perception of intrinsic and extrinsic motivation: effects on institutionalized mentally retarded adolescents.

Self-perception theory predicts that the introduction of extrinsic rewards for behavior that was intrinsically rewarding may decrease rather than enhance overall motivation. This hypothesis was tested on a group of institutionalized mentally retarded adolescents (34 boys, 10 girls). Intrinsic (high and low task interest) and extrinsic (high- and low-incentive objects) motivation were both manipulated as independent variables, and the dependent variable was task persistence during a free-play period. Results indicated that for a high intrinsically interesting task, the task persistence was greater under the external reward of low- rather than high-incentive value conditions. The opposite trend was revealed for the low intrinsically interesting task. The results provided some evidence that the greater the amount of the reward for an interesting activity, the greater the degree to which the intrinsic interest is undermined.