International Journal of Comparative Psychology

Four experiments were conducted to determine why rhesus monkeys ( Macaca mulatta ) perform so poorly on a visuospatial memory test modeled after a popular children’s game (Concentration). In these studies, four different memory tasks were administered to ascertain whether monkeys show limitations in visual memory (memory for which images had been seen), limitations in spatial memory (limitations of what locations had been visited), or limitations in the coordination of these two modalities (memory for what images are located where). The data indicate that the monkeys could remember visual information when there were no spatial demands. The monkeys could also remember spatial information when there were no visual-memory demands, although performance on this spatial-memory task was not as accurate as had been predicted. However, when visual and spatial memories had to be coordinated–memory for what was where–performance was no better than chance. Hypotheses were discussed for why the monkeys, but not human participants, struggle to coordinate visual and spatial memory. Perhaps this represents and area where humans use verbal working memory—a mnemonic strategy that is presumably unavailable to nonhuman primates—to facilitate the maintenance and cross-referencing of visual and spatial information.