Selected cognitive developments presumed to mediate the development of achievement motivation are described. Age trends for four causal schemes involving the concepts of effort and ability from 5 to 13 years of age are presented. Developments related to ability, task difficulty, and incentive value are also described. (Author/JMB)

Deals with (1) developmental changes in children's concepts of difficulty and ability and (2) individual differences within different developmental levels. Three levels of understanding of ability and difficulty are proposed, and cross-sectional and longitudinal evidence of progressive development through the stages is presented. (Author/RH)