The role of graded category structure in imaginative thought.

Participants generated lists of exemplars from the categories of animals, tools, and fruit, and their lists were used to determine the relative accessibility of individual exemplars. Measures of accessibility included output dominance (the number of participants who listed an exemplar), rank (how early instances were listed), and two scores that reflect their combination-output precedence and dominance/rank. Other participants drew and described novel exemplars of those categories that might exist on an imaginary planet and reported on the factors that influenced their creations. References to Earth animals, tools, or fruit were used to determine imagination frequency (the number of participants who mentioned relying on particular Earth exemplars). Items high in accessibility were also high in imagination frequency, implying that those items that come to mind most readily are the ones most likely to serve as starting points for the development of novel ideas. This result held even when task constraints weighed against the use of such items (Experiment 2) and when participants were encouraged to be as creative as possible (Experiment 4), suggesting that it is difficult to avoid the influence of highly accessible category exemplars. Other measures of category structure, including the rated typicality, familiarity, and frequency of exemplars, did not predict imagination frequency as well. The results are discussed in terms of expanding concept boundaries and the inadvertent application of knowledge that is readily accessible.