Category size and judgments of variability: The effects of seeing the trees in the forest1


  • 1

    The research reported in this article was conducted when the authors were both at the University of California, Los Angeles. The study was supported in part by a Fulbright Scholarship granted to the first author and funding from the US National Science Foundation (BNS# 8908681) awarded to the second author. E-mail may be addressed to


Abstract: Competing predictions about the effects of category size on judgments of category variability were examined in two studies involving the presentation of exemplars of two artificial social groups. In contrast to predictions of some exemplar-based models, Experiment 1 demonstrated that a numerically smaller group was perceived to be more variable than a larger group on the standard deviation measure of frequency distribution estimates. The result was interpreted to be an effect of differential information load. Experiment 2 revealed that variability judgments were influenced by prior expectations about the central tendencies as well as by practice in retrieving information about category exemplars. When frequency distribution estimates were made subsequent to abstract tasks, expectations about the numerical majority reduced perceived variability, while this influence was mitigated when memory measures preceded the frequency estimates.