Object Individuation In The Absence Of Kind-Specific Surface Features: Evidence For A Primordial Essentialist Stance?

It has been suggested that due to functional similarity, sortal object individuation might be a primordial form of psychological essentialism. For example, the relative independence of identity judgment from perceived surface features is a characteristic of essentialist reasoning. Also, infants engaging in sortal object individuation pay more attention to kind than surface feature information when judging the identity of objects (e.g.). Indeed, previous research found that 14-month-old infants can judge trans-temporal identity even in complete absence of kind-specific surface features. Here, we used another more demanding non-linguistic paradigm to test the limits of these abilities in 14-, 18-, 23- and 36-monthold infants, comparing their performance to recent great ape data. Particularly, we presented infants with two food kinds, whose surface features were then fully transformed to make them look identical. If reasoning according to essentialist principles, participants should select the preferred item despite superficial manipulations. However, only 36- month-olds reliably tracked the preferred item after superficial manipulations. This suggests that, although basic psychological essentialism may emerge early in infancy, more complex forms require domain-general cognitive prerequisites, which only develop in more protracted form.