On the development of the augmentation principle: a perceptual approach.

Previous research in the development of causal schemata has relied upon verbal descriptions of behavior to convey causally relevant information. In the present study, however, a perceptual analogue of Kelley's augmentation principle was created in animated films depicting the movements of 2 objects toward a goal--1 which overcame an obstacle (inhibitory cause present) and 1 which did not (inhibitory cause absent). Both forced-choice and scalar measures indicated that kindergarten, second, and fourth graders all perceived greater motivation (internal facilitative cause) in the inhibited than noninhibited object, but that age differences emerged in the ability to explain these responses. In a second experiment, the 2 target objects were inhibited by obstacles of different sizes. For this quantitative version of the principle, age differences emerged for all measures; fourth graders and most second graders responded in accord with augmentation-principle predictions. These results were compared with the earlier findings that kindergarten and fourth-grade children did not understand this principle. The contrasting methods of stimulus presentation were discussed and implications of this technique for attribution research were noted.