Linear Separability and Concept Learning: Eyetracking Individual Differences

Asking people whether a tomato is fruit, or whether chess is a sport, reveals differences between individuals’ concepts. How can the same perceptual information result in different representations? Perhaps people’s initial attention to particular category information determines what representations they will form. When first learning about chess, for example, attention to its competitive aspect may cause one to classify it as a sport, whereas attention to its non-athletic nature will cause one to classify it as a game. Early research focused not on individual differences but rather on questions such as whether people can learn nonlinearly separable (NLS) categories, (as predicted by exemplar memorization), or whether they favor linearly separable (LS) categories (as predicted by prototype abstraction). Indeed, it is generally believed that this question was laid to rest by Medin and Schwanenflugel (1981), who found that NLS can be learned as easily as LS categories. However, Blair and Homa (2001) in fact found individual differences, with some subjects favoring LS, others NLS categories, and others neither. The present study investigates why individuals might prefer LS over NLS categories, or vice versa. We do this in a novel and direct way, by using categories with independently predictive dimensions that provide an LS solution, and additional, configurally predictive dimensions that provide an NLS solution.