Michael J. Beran, Ph.D.
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September 1, 2021



Beran, M. J., Beran, M. M., & Menzel, C. R. (2005). Spatial memory and monitoring of hidden items through spatial displacements by chimpanzees (Pan troglodytes). Journal of Comparative Psychology, 119, 14-22.

In this study we examined chimpanzee short-term memory for food location in near space. In Experiment 1, chocolate pieces were hidden beneath 2 of 5 opaque cups. The 2 chimpanzees tested remembered the locations of both items when the array remained stationary, but they remembered the location of only one item when the array was rotated 180 degrees. In Experiment 2, 1 chocolate was hidden in an array of 3 cups, and the array of cups was rotated either 180 degrees or 360 degrees. Performance was high in both conditions. In Experiment 3, 2 chocolates were hidden beneath 2 of 7 cups, and the 4 chimpanzees tested found both hidden items at levels better than chance. 90% of errors were made after 1 of the 2 items had been found. Those errors were more frequently made at locations adjacent to the remaining hidden item than at locations adjacent to the already recovered item. Thus, chimpanzees tracked the nonvisible movement of at least one hidden item in an array of identical cups. When performance deteriorated, it most likely did so because of memory failure rather than as a failure of inhibitory control.

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