Spontaneous Object Recognition in Animals: A Test of Episodic Memory

Abstract

Episodic memory is characterized by Tulving (1983, 2002) as a discrete form of memory that involves mentally re-enacting previously experienced events. Traditionally, the investigation of episodic memory has been restricted to human subjects because the ability to mentally re-enact past experiences suggests that it requires self-consciousness and the ability to mentally travel forward and backward in time (Tulving, 1983, 2002). Because of the difficulty of demonstrating these abilities without the use of complex verbal language, many believed that episodic memory could not be studied in non-humans. However, through a series of elegant experiments, Clayton, Dickinson and their colleagues (e.g., Clayton & Dickinson, 1998) have developed a paradigm that allows researchers to model some aspects of episodic memory in non-humans. In particular, they focus on the abilities of food-caching birds to represent the “what/where/when” of an event into a single tripartite code. While this model has opened up the field of episodic memory to testing in non-humans, it is not easily applied to non-caching species. More recently, Eacott and Norman (2004) have developed a paradigm using object recognition that allows researchers to model episodic memory in a wider variety of non-human animals. Their paradigm involves altering the “what/where/when” code of Clayton and Dickinson to a tripartite code consisting of “what/where/which.”