The relationships among the perception, representation, and construction of series are examined within a model of the acquisition of seriation abilities. The model is then related to two experiments with three-, four- and five-year-olds. The key feature of the model is the delineation of parallels among developmental changes in three arenas:…

Demonstrated is a covariance principle that causes the observer to assume that if one aspect of a two-dimensional figure (its perimeter or its area) is conserved, the other aspect must also be conserved (pseudo-conservation). Mentally retarded individuals, assuming no such fixed relationship, correctly judged the changed state of the nonconserved…