Object Permanence in the Pigeon (Columba livia): Insertion of a Delay Prior to Choice Facilitates Visible- and Invisible-Displacement Accuracy

Object permanence, often viewed as a measure of human cognitive development, has also been used to assess animals' cognitive abilities. Tests of object permanence have distinguished between visible displacement, in which an object may be placed into one of two (or more) containers to be retrieved, and invisible displacement, in which after the object is placed into the container, the container is moved before retrieval is attempted. We tested pigeons' accuracy on both visible and invisible displacement using a rotational beam with a container at either end. In Experiment 1, the pigeons showed some evidence of object permanence on an initial visible displacement test, but they did not maintain accurate choice. With training, their accuracy improved but only to about 70% correct. When tested on a 90 degrees invisible displacement (rotation), accuracy transferred but once again dropped with further training. In Experiment 2, a 5-s delay was inserted between container baiting and choice. Once again, the pigeons showed some evidence of object permanence on an initial visible displacement test, although on the first test session, choice accuracy was not much better than in Experiment 1. With training, choice accuracy improved greatly. Furthermore, pigeons showed good transfer when they were tested on the 90 degrees invisible displacement. Finally, and importantly, they also transferred well to a 180 degrees invisible displacement, a displacement on which dogs failed. The results of these experiments suggest that under the right conditions, pigeons can show a moderate degree of object permanence.