A study was conducted to test the hypothesis that metaphorical thought develops according to the principles governing other categorizing processes. Of particular interest were the questions of whether preschool children possess the categorical flexibility to comprehend metaphorical statements and, if they do, whether this flexibility manifests…

Conservation performance during childhood to portions of the life span beyond adolescence is examined, with existing data replicated on subjects ranging from the preschool to middle-childhood years. Age differences in performance are studied for the typical Piagetian paired-stimulus equivalence conservation of number, substance, weight, and volume…