Go when you know: Chimpanzees' confidence movements reflect their responses in a computerized memory task.
Michael J Beran, Bonnie M Perdue, Sara E Futch, J David Smith, Theodore A Evans, Audrey E Parrish
Author Information
Michael J Beran: Language Research Center and Department of Psychology, Georgia State University, United States. Electronic address: mjberan@yahoo.com.
Bonnie M Perdue: Department of Psychology, Agnes Scott College, United States.
Sara E Futch: Department of Psychology, Wofford College, United States.
J David Smith: Department of Psychology, University at Buffalo, The State University of New York, United States.
Theodore A Evans: Language Research Center, Georgia State University, United States.
Audrey E Parrish: Language Research Center and Department of Psychology, Georgia State University, United States.
Three chimpanzees performed a computerized memory task in which auditory feedback about the accuracy of each response was delayed. The delivery of food rewards for correct responses also was delayed and occurred in a separate location from the response. Crucially, if the chimpanzees did not move to the reward-delivery site before food was dispensed, the reward was lost and could not be recovered. Chimpanzees were significantly more likely to move to the dispenser on trials they had completed correctly than on those they had completed incorrectly, and these movements occurred before any external feedback about the outcome of their responses. Thus, chimpanzees moved (or not) on the basis of their confidence in their responses, and these confidence movements aligned closely with objective task performance. These untrained, spontaneous confidence judgments demonstrated that chimpanzees monitored their own states of knowing and not knowing and adjusted their behavior accordingly.
