EVIDENCE FOR A NEO-PIAGETIAN STAGE TRANSITION IN EARLY COGNITIVE-DEVELOPMENT

Criticisms of Piaget's stage theory have led neo-Piagetians to redefine stage change as an age-related-and possibly spurt-like-shift in the level of diverse cognitive operations. This study tests a hypothesised stage shift according to this definition, using longitudinal methodology in the period of early infancy. Case's theory of development predicts a stage transition beginning at about 4 months. To test this prediction, infants' performance on a battery of six sensorimotor tasks was examined weekly as they crossed the age range between 2.5 and 5.5 months. For all tasks, a pass rate of 50% was first observed between 3.7 and 4.6 months, and task profiles showed some evidence of clustering or synchrony. In addition, onset age data indicated intra-individual synchrony in task acquisitions, suggesting discontinuous or spurt-like changes in overall development. These results are consistent with a neo-Piagetian definition of stage change, and lend support to Case's model of early cognitive development.