Water-level task

The water-level task is an experiment in developmental and cognitive psychology developed by Jean Piaget and Bärbel Inhelder. The experiment attempts to assess the subject's spatial reasoning. The subject is shown an upright bottle or glass with a water level marked, then shown pictures of the container tilted at different angles without the level marked and asked to mark where the water level would be. Piaget and Inhelder developed the test as part of their work on child development. It was first described in their book The Child's Conception of Space, published in French in 1948, with an English translation appearing in 1956. They described a series of stages children pass through in their understanding, corresponding to different modes of performance on the water-level test, before mastering it around the age of nine. In 1964, Freda Rebelsky reported the surprising result that a significant number of her undergraduate and graduate students failed the task, and that the rate of failure was higher among female students. These results have since been replicated in a number of studies, and most subsequent interest in the water-level task has been concerned not with the study of child development but rather with accounting for the adults and adolescents that fail the test, and the apparent difference in success rates between the sexes.