Cognitive coordinate systems: Accounts of mental rotation and individual differences in spatial ability.

Strategic differences in spatial tasks can be explained in terms of different cognitive coordinate systems that subjects adopt.The strategy of mental rotation that occurs in many recent experiments uses a coordinate system denned by the standard axes of our visual world (i.e., horizontal, vertical, and depth axes).Several other possible coordinate systems (and hence other strategies) for solving the problems that occur in psychometric tests of spatial ability are examined in this article.One alternative strategy uses a coordinate system denned by the demands of each test item, resulting in mental rotation around arbitrary, taskdefined axes.Another strategy uses a coordinate system denned exclusively by the objects, producing representations that are invariant with the objects' orientation.A detailed theoretical account of the mental rotation of individuals of low and high spatial ability, solving problems taken from psychometric tests, is instantiated as two related computer simulation models whose performance corresponds to the response latencies, eye-fixation patterns, and retrospective strategy reports of the two ability groups.The main purpose of this article is to provide a theory of how people solve problems on psychometric tests of spatial ability, focusing on the mental operations, representations, and strategies that are used for different types of problems.The theory is instantiated in terms of computer simulation models whose performance characteristics resemble human characteristics.A second purpose of the article is to analyze the processing differences between people of high and low spatial ability.One computer model simulates the processes