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I outline the perspective that searching the contents of memory is a form of mental time travel in nonhumans that is relatively tractable because it focuses on the contents of memory. I propose that an animal model of mental time travel requires three elements: (1) the animal remembers multiple events using episodic memory, (2) the order of events in time is included in the representation, and (3) the sequence of events can be searched to find a target that occurred at a particular time. I review experiments suggesting that rats represent multiple items in episodic memory (Element 1) in order of occurrence (Element 2) and engage in memory replay to search representations in episodic memory in sequential order to find information at particular points in the sequence (Element 3). The cognitive building blocks needed for mental time travel may be quite old in the evolutionary timescale.
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This content will become publicly available on January 21, 2026
Episodic memory in nonhumans: An approach to understand an evolutionary function of consciousness
A fundamental question in comparative cognition concerns the evolution of consciousness. It is unlikely that consciousness appeared in humans without any precursors in other animals. Yet, the concepts that dominate our understanding of consciousness are inherently human centered, focusing on subjective experiences with a rich use of language. This understanding of consciousness is likely empirically intractable in studies of nonhumans. An alternative approach focuses on adopting a functional perspective. What function does consciousness serve? What can an animal capable of such a function do via its behavior? In this connection, I review the development of animal models of episodic memory. Episodic memory involves recalling the past and in humans is described as the phenomenological conscious experience of projecting oneself (autonoesis) in time (chronesthesia). Because there are no agreed upon empirical approaches to investigate subjective experiences in nonhumans, efforts to develop animal models of episodic memory have focused on the contents of episodic memory. I review experiments using rats that suggest that, at the moment of a memory assessment, the animal remembers back in time to an earlier event or episode. I conclude by evaluating implications of episodic memory in rats as a functional window into the evolution of consciousness.
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- Award ID(s):
- 1946039
- PAR ID:
- 10568482
- Publisher / Repository:
- The Royal Society
- Date Published:
- Journal Name:
- Philosophical transactions Royal Society Biological sciences
- ISSN:
- 0962-8436
- Subject(s) / Keyword(s):
- Episodic memory what-where-when memory source memory incidental encoding and unexpected question replay, episodic-like memory
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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