Twenty first and 20 fourth grade children were tested on perceptual tasks involving moving stimuli that did not touch. In these tables, one stimulus appeared, among adults, to cause the other to move. (MS)

Attempts to clarify the basis for the unusual responses to observed movement by 7-year-old children, as compared to adults, discovered by Olum. Subjects were 40 first and third graders. Results indicate that these responses are genuine and that they go through a developmental evolution. (SDH)

Compared the performance of 29 institutionalized cultural-familial mental retardates on Piagetian conservation tasks. Examined the effects of age, sex, and degree of retardation on conservation performance. (BD)