The coding and transformation of spatial information

The present paper examines the mental processes involved in inferring perspective changes that result either from the rotation of a spatial array or from the rotation of the viewer of that array. Piaget has shown that viewer-rotation problems are difficult when children must choose among pictures or models of an array from differing perspectives. We showed earlier that, with parallel tasks, array-rotation problems are much easier than viewer-rotation problems. We proposed that in solving these problems, subjects interpret the instructions literally, recoding the position of the viewer vis-à-vis the array for viewer-rotation problems and recoding the array with respect to its spatial framework for arrayrotation problems. At that time, we proposed a second principle to explain why Piagetian perspective problems are so difficult; namely, that children have special difficulty in recoding viewer position (egocentrism). The present experiments show that, when subjects are asked a different sort of question on such tasks, viewer-rotation problems become easy and array-rotation problems become difficult. The results show that the difficulty of the Piagetian perspective task is not due to egocentrism; i.e., to difficulty recoding viewer position. The results of all these rotational-transformation tasks can be explained if we add a different second principle to the principle of literalness of problem interpretation. This new second principle posits that the array is fixed vis-à-vis the spatial context rather than that the viewer is fixed vis-à-vis the array.