Landmark use by squirrel monkeys (Saimiri sciureus)

Abstract

Two squirrel monkeys searched for a reward buried in 1 of 144 holes that formed a 12×12 grid (48×50 cm). An array of vertical, colored landmarks was placed on the grid, and their locations on the grid were changed from trial to trial. During training trials, the mealworm reward was placed either in the center of a square array of landmarks (Experiments 1 and 3) or midway between two landmarks (Experiment 2). On nonrewarded test trials, the monkeys searched among landmarks placed in the same arrays as those used in training and among landmarks placed in an expanded array (Experiments 1 and 2) or in an array intermediate between the two arrays used in training (Experiment 3). Distributions of searches on test trials indicated that the monkeys searched mostly within the configuration of the landmarks but that they had not coded the location of the reward as being either in the middle of the landmarks or at a fixed distance and direction from an individual landmark.