Implicit and explicit category learning by capuchin monkeys (Cebus apella)

TitleImplicit and explicit category learning by capuchin monkeys (Cebus apella)
Publication TypeJournal Article
Year of Publication2012
AuthorsJ Smith, D., Crossley M. J., Boomer J., Church B. A., Beran M. J., & F Ashby G.
JournalJournal of Comparative Psychology
Date Published2012 Aug
KeywordsAnimals, Cebus, Discrimination Learning, Female, Judgment, Male, Photic Stimulation, Visual Perception

Current theories of human categorization differentiate an explicit, rule-based system of category learning from an implicit system that slowly associates regions of perceptual space with response outputs. The researchers extended this theoretical differentiation to the category learning of New World primates. Four capuchins (Cebus apella) learned categories of circular sine-wave gratings that varied in bar spatial frequency and orientation. The rule-based and information-integration tasks, respectively, had one-dimensional and two-dimensional solutions. Capuchins, like humans, strongly dimensionalized the stimuli and learned the rule-based task more easily. The results strengthen the suggestion that nonhuman primates have some structural components of humans' capacity for explicit categorization, which in humans is linked to declarative cognition and consciousness. The results also strengthen the primate contrast to other vertebrate species that may lack the explicit system. Therefore, the results raise important questions about the origins of the explicit categorization system during cognitive evolution and about its overall phylogenetic distribution.

Alternate JournalJ Comp Psychol
PubMed ID22023264
PubMed Central IDPMC3531231
Grant ListR01 MH3760-2 / MH / NIMH NIH HHS / United States
P01 HD038051 / HD / NICHD NIH HHS / United States
R01 HD061455 / HD / NICHD NIH HHS / United States
HD-060563 / HD / NICHD NIH HHS / United States
3P01HD038051-10S1 / HD / NICHD NIH HHS / United States
P01 HD060563 / HD / NICHD NIH HHS / United States