Orangutan strategies for solving a visuospatial memory task

The popular game known as Concentration (also commonly referred to as Memory), in which players search for matching pairs among a grid of face-down cards, provides a robust platform for examining visuospatial memory in a simple and nonverbal way. Five orangutans (Pongo ssp.) at the Indianapolis Zoo were given a modified version of the Concentration Game in which three cards were shown face-down on a computer screen, two of which matched each other while the third was a foil. Subjects overturned two cards at a time by touching them, with trials terminating in a food reward if the overturned cards matched, or reverting to their face-down position if they did not. A constraint was experimentally imposed on the game whereby the first two cards touched would never match, resulting in an optimal strategy composed of touching the first two cards, followed by the third, followed by the card among the first two cards that matched the third. We aimed to measure the extent to which orangutans would memorize and utilize visuospatial cues to solve the task in the optimal manner. Findings showed that three of five subjects utilized an optimal strategy more often than would be expected by chance, but also over utilized specific patterns of choices instead of adjusting their strategies to minimize the overall number of card flips. Visuospatial recall played a role in several of the participants' strategies for completing the task, but not to an extent that was necessary to achieve optimal gameplay.