Metamorphosis: Essence, appearance, and behavior in the categorization of natural kinds

Abstract

The transformation paradigm (Rips, 1989) was used to contrast causal homeostasis and strict essentialist beliefs about biological kinds. Participants read scenarios describing animals that changed their appearance and behavior through either accidental mutation or developmental maturation and then rated the animals on the basis of similarity, typicality, and category membership both before and after the change. Experiment 1 in the present study replicated the dissociation of typicality and categorization reported by Rips (1989) but also revealed systematic individual differences in categorization. With typicality and membership ratings collected between participants, however, Experiment 2 found no evidence for the dissociation and few essentialist responders. In Experiment 3, excluding information about offspring led most participants to categorize on the basis of appearance and behavior alone. However, with offspring information included and with questioning focused on the change of kind, essentialist categorization was still surprisingly rare. We conclude that strict essentialist categorization in the transformation task is relatively rare and highly task dependent, and that categorization is more commonly based on causal homeostasis.

Individual differences in the perception of similarity and difference

“…Indeed, we have found elsewhere that some participants exhibit a systematic dissociation of similarity and categorization judgments, while other participants exhibit no such dissociation (Hampton, Estes, & Simmons, 2007). Thus, research on categorization suggests that different individuals may perceive similarity in very different ways.…”

Classification as diagnostic reasoning

“…In a replication of Rips (1989), Hampton et al (2007) found that whether a transformed animal was judged to have changed category membership often depended on what the participants could infer about underlying causal processes and structures. The participants in these studies were told a story about, for example, a bird that had normal bird-like features (it had feathered wings, ate seeds, lived in a nest in a tree, etc.)…”

“…For example, in Keil's (1989) well-known transformation experiments, second graders were told about doctors who dyed a raccoon's fur black, bleached a white stripe down its back, and put a sac of odor in its body. The children judged that the transformed animal was still a raccoon, despite its now looking like a skunk, reflecting the importance of the animal's internal versus external properties (see Rips, 1989, andHampton, Estes, &Simmons, 2007, for related findings with adults). In fact, evidence that the internal structure of animals is more important than the outside has been found with children as young as 3 years old (Gelman & Wellman, 1991; also see Diesendruck, 2001, Gelman, 2003, and Hirschfeld, 1996.…”

Contingent necessity versus logical necessity in categorisation

“…For example, Larochelle, Cousineau, and Archambault (2005) observed that reported critical features 6 necessary features were not actually treated as such in decisions about category membership. Also, Hampton, Estes, and Simmons (2007) argued that high variance in individual participant performance could have partly accounted for the dissociation Rips reported and also found that changing particular aspects of the stimuli Rips used eliminated essentialist classification. However, researchers have often reported effects that look like critical feature effects (for example, Rips, 1989).…”

“…The problem with essentialism as a psychological theory is that, if essences are not known (or do not even exist! ), it seems difficult to construct well-controlled supporting experiments (for attempts see Gelman, 2003, Hampton, Estes, & Simmons, 2007Pothos, Hahn, & Prat-Sala, 2009). …”