The Psychological Organization of "Uncertainty" Responses and "Middle" Responses: A Dissociation in Capuchin Monkeys (Cebus apella)

Michael J. Beran, J. David Smith, Mariana V.C. Coutinho, Justin J. Couchman, Joseph Boomer

Research output: Contribution to journalArticlepeer-review

74 Citations (Scopus)


Some studies of nonhuman animals' metacognitive capacity encourage competing low-level, behavioral descriptions of trial-decline responses by animals in uncertainty-monitoring tasks. To evaluate the force of these behavioral descriptions, the authors presented 6 capuchin monkeys (Cebus apella) with 2 density discrimination tasks between sparse and dense stimuli. In one task, difficult trials with stimuli near the middle of the density continuum could be declined through an "uncertainty" response. In the other task, making a "middle" response to the same stimuli was rewarded. In Experiment 1, capuchins essentially did not use the uncertainty response, but they did use the middle response. In Experiment 2, the authors replicated this result with 5 of 6 monkeys while equating the overall pace and reinforcement structure of the 2 tasks, although 1 monkey also showed appropriate use of the uncertainty response. These results challenge a purely associative interpretation of some uncertainty-monitoring performances by monkeys while sharpening the theoretical question concerning the nature of the psychological signal that occasions uncertainty responses.

Original languageEnglish
Pages (from-to)371-381
Number of pages11
JournalJournal of Experimental Psychology: Animal Behavior Processes
Issue number3
Publication statusPublished - Jul 2009
Externally publishedYes


  • capuchin monkeys
  • comparative cognition
  • metacognition
  • primate cognition
  • uncertainty monitoring

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Experimental and Cognitive Psychology


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