Elsevier

Behavioural Processes

Volume 72, Issue 2, 1 May 2006, Pages 173-183
Behavioural Processes

Mental time travel in animals: A challenging question

https://doi.org/10.1016/j.beproc.2006.01.009Get rights and content

Abstract

Humans have the ability to mentally recreate past events (using episodic memory) and imagine future events (by planning). The best evidence for such mental time travel is personal and thus subjective. For this reason, it is particularly difficult to study such behavior in animals. There is some indirect evidence, however, that animals have both episodic memory and the ability to plan for the future. When unexpectedly asked to do so, animals can report about their recent past experiences (episodic memory) and they also appear to be able to use the anticipation of a future event as the basis for a present action (planning). Thus, the ability to imagine past and future events may not be uniquely human.

Section snippets

Looking backward—episodic memory in animals

A more embedded cognitive process is the ability to mentally travel backward in time. The ability of humans to visualize a past event that was personally experienced, referred to as episodic memory, is meaningful because each of us has subjectively reexperienced past events. The distinction between the reexperience of personally experienced events (episodic memory) and the retrieval of factual information or rules (semantic memory) was proposed by Tulving (1972). The presumption is that

Looking forward—planning for the future

Although we may be unable to determine whether animals have episodic memory, which was our original concern, we may be able to ask whether animals can plan for the future. In a simplistic sense, the answer is certainly yes. Birds build nests into which they will lay eggs, and bears hibernate in the winter to reduce their caloric loss during times when food is relatively scarce. However, from a cognitive perspective, such planning occurs under close genetic control and would not be considered to

Conclusions

Evidence from research on episodic memory in animals suggests that when unexpectedly asked to do so, pigeons are able to retrieve their own behavior (whether they had just pecked or not) or the occurrence of an important event (whether or not they had just been fed). Such data are more in keeping with the implied questions asked in human episodic memory experiments than with the ‘what, where, and when’ questions presumed to provide evidence for episodic memory.

If the function of mentally

Acknowledgements

Preparation of this manuscript and some of the research reported here was supported by National Institute of Mental Health Grant MH-59194. I thank Marcia Spetch and two anonymous reviewers for their helpful comments on an earlier version of the manuscript.

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