The water-level task is an

experiment An experiment is a procedure carried out to support or refute a hypothesis, or determine the efficacy or likelihood of something previously untried. Experiments provide insight into cause-and-effect by demonstrating what outcome occurs whe ...

in developmental and

cognitive psychology Cognitive psychology is the scientific study of human mental processes such as attention, language use, memory, perception, problem solving, creativity, and reasoning. Cognitive psychology originated in the 1960s in a break from behaviorism, whi ...

developed by

Jean Piaget Jean William Fritz Piaget (, ; ; 9 August 1896 – 16 September 1980) was a Swiss psychologist known for his work on child development. Piaget's theory of cognitive development and epistemological view are together called genetic epistemology. ...

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 Child development involves the Human development (biology), biological, psychological and emotional changes that occur in human beings between birth and the conclusion of adolescence. It is—particularly from birth to five years— a foundation ...

. 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 A student is a person enrolled in a school or other educational institution, or more generally, a person who takes a special interest in a subject. In the United Kingdom and most commonwealth countries, a "student" attends a secondary school ...

. 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.

Sex differences in performance

It is difficult to give the precise fraction of men and women that fail the water-level task, since this is sensitive to the methodological details of how the task is presented and scored, but the finding that men perform at a higher level has been robustly confirmed. One typical study from 1989 found that 32% of college women failed the test, compared to 15% of college men. A 1995 experiment found that 50% of undergraduate males and 25% of females performed "very well" on the task and 20% of males and 35% of females performed "poorly". Similar sex differences have been confirmed internationally. The difference in performance between men and women has been estimated, in terms of Cohen's ''d'', to be between 0.44–0.66 (i.e. between 0.44 and 0.66

standard deviation In statistics, the standard deviation is a measure of the amount of variation of the values of a variable about its Expected value, mean. A low standard Deviation (statistics), deviation indicates that the values tend to be close to the mean ( ...

s).

References

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