Rapid learning of a spatial memory task in a lacertid lizard (Podarcis liolepis)

Abstract

Mammals and birds are capable of navigating to a goal using learned map-like representations of space (i.e. place learning), but research assessing this navigational strategy in reptiles has produced inconclusive results, in part due to the use of procedures that do not take account of the peculiarities of reptilian behavior and physiology. Here I present a procedure suitable for testing spatial cognition that exploits a naturally evolved, ethologically relevant ability common to many lizards (i.e. refuge seeking behavior). The procedure requires lizards to learn the location of an open refuge inside a rectangular arena containing artificial refuges in every corner, using distal extramaze visual cues and with no local cues marking the location of the open refuge. The procedure probes the lizards’ place learning ability and effectively rules out the use of egocentric and response-based strategies. The described procedure was successfully used to demonstrate place learning in a lacertid lizard (Podarcis liolepis). Over the course of two weeks of training both the latency to entering the open refuge and the number of corners visited in each trial decreased gradually, indicating that learning had taken place in over 60% of the lizards tested. These results confirm that, under certain circumstances, lizards are capable of navigating to a goal using a place learning strategy.