Abstract
Four studies examined adults' and children's understanding of polymorphs -- organisms that undergo a radical transformation (e.g., caterpillar-butterfly) -- which have been used as critical tests of essentialism in concepts. In Study 1, adults judged the similarity of juvenile organisms to their adult versions and perceptual controls; in Study 2, children made forced-choice similarity judgments. Both age groups were influenced by both biological and perceptual relatedness. Age differences were largely explainable by children's knowledge of the particular metamorphosis rather than changes in overall strategy. In Study 3, adults made inductions of different kinds of properties from juveniles to other animals; biological relatedness was most important for “deep$rdquo; properties and perceptual resemblance for “superficial$rdquo; properties. Study 4 tested children's inductions on biological properties and found results paralleling their similarity judgments. These studies revealed that children and adults use both the biological relation across life stages and perceptual⁄morphological similarity in their thinking about these organisms. Development was largely in the direction of being better able to coordinate these two sources of information. The findings speak against accounts that emphasize perception or underlying knowledge alone.
