Notes that the Piagetian perspective admits the existence of interindividual differences but interprets them as noise masking the universal logical succession of structures, whereas the differential perspective views development as consisting of "vicarious processes." Asserts that the main aim of the "procedural studies"…

Reports a series of studies conducted to investigate possible differences in the exploratory manipulation and play behavior of human infants 7-1/2- 11-1/2 months of age as a function of the attributes of the stimulus, the familiarity of the subject with the stimuli, the age and sex of the infants, and individual differences. (Author/CS)

In this study an attempt was made to obtain a developmental dimension for estimating longitudinal development on the basis of cross-sectional data. To check the validity of this approach, the cross-sectional data were compared with true longitudinal data. Forty-three public school children were given a series of conservation tasks in four…

The relative development of Piagetian concrete logical operational abilities was investigated in Mexican American and Anglo American children. Performance was assessed on eight classification tasks and three forms of transitivity, measuring seriation skills. One phase of the study compared the performances of 30 Anglo and 30 Mexican American…