To investigate developmental differences in timesharing performance, 60 boys, 20 in each of three age groups (7-, 10- and 13-year-olds), performed an auditory matching task and a tracking task alone and concurrently, the latter under two sets of instructions. Decrements produced by concurrent performance were compared for the three age groups.…

Piaget, in describing the sequence of classificatory development, describes class inclusion as composed of two processes; hierarchical classification and post-whole comparisons. In the experiment reported here, elementary school children, trained in the concept of sets in first grade mathematics were given a task where they were required to assess…

In this part of the Kansas City Study of Adult Life, educational implications of adult activities and goals were explored, with emphasis on effective living in middle life. Performance of adult developmental tasks and motivation toward effort in these areas were investigated. Criteria were offered for assessing high, medium, and low performance in…