Adult's failures on euclidean and projective spatial tasks: Implications for characterizing spatial cognition

In their initial study of the development of children's spatial concepts, Piaget and Inhelder (1956) designed the “water-level” and “plumb-line” tasks to assess children's Euclidean abilities to perceive and represent horizontals and verticals. Surprisingly, subsequent research has shown that many adults perform badly on these tasks designed for children. Here we studied whether adults (N=160) would also have difficulty on a shadow projection task developed to assess theoretically related projective spatial concepts. The data showed that some adults had difficulty on the shadow task, whether tested by a drawing or by a selection task, and whether scored with respect to qualitative shape or metric accuracy. Performance was significantly worse on complex than simple forms, and when sex differences emerged, they favored males. As hypothesized, the best predictor of shadow performance was performance on the Euclidean tasks. Scores on the Embedded Figures Test and participant sex accounted for small (but significant) additional variance on shadow performance. Implications for theories of spatial development and for modeling individual differences in spatial cognition are discussed.