A Scalogram Study of Classificatory Development

The technique of scalogram analysis was employed to test Piaget's theory that there is a fixed order in which classificatory concepts are acquired. It was hypothesized that there are 11 steps by which children learn to build upon simple equivalence groupings to attain the concept of class inclusion. When these steps were translated into tasks and administered to 122 Ss between 4 and 9 years of age: (a) there was a significant correlation between S's age and the number of tasks mastered; (b) the order of difficulty of the tasks corresponded to the predicted order; (c) there was no set order of mastery such that passage of a more difficult item invariably implied passage of all the easier items; (d) for each task there were no age differences among Ss who made different kinds of errors.