Singh, Gupta, and Dalal proposed that American and Indian college students differ in their cultural outlook on how motivation and ability determine performance. Americans follow a multiplying rule which implies that effort will be more effective with persons of high than low ability. In contrast, Indians follow a constant-weight averaging which implies that effort will be equally effective with persons of low and high ability. The present study made a more thorough test of this cultural-difference hypothesis, using subjects from five age groups. As predicted, subjects averaged information about past performance, motivation, and ability of the stimulus student in attribution of his performance. There was no support for Heider's suggestion and American finding that Performance = Motivation X Ability. Developmental differences appeared at the level of information processing and integrational capacity. These results illustrate the potential power that information integration theory provides for cross-cultural and cross-age comparisons in social perception.