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Rethinking the Definition of Episodic Memory
Christopher R. Madan
University of Nottingham
The definition of episodic memory, as proposed by Tulving, includes a requirement of conscious recall.
As we are unable to assess this aspect of memory in nonhuman animals, many researchers have referred
to demonstrations of what would otherwise be considered episodic memory as “episodic-like memory.”
Here the definition of episodic memory is reconsidered based on objective criteria. While the primary
focus of this reevaluation is based on work with nonhuman animals, considerations are also drawn from
converging evidence from cognitive psychology, neuropsychology, and cognitive neuroscience. Impli-
cations of this rethinking are discussed, as well as considerations of familiarity, indirect measures of
memory, and generally what should be viewed as necessary for episodic memory. This perspective is
intended to begin an iterative process within the field to redefine the meaning of episodic memory and
to ultimately establish a consensus view.
Public Significance Statement
Being able to remember our past experiences, such as the specific event details from a recent dinner
with friends or when you moved to a new city, rely on episodic memory. Based on the conventional
definition proposed by Endel Tulving decades ago, only humans have episodic memory and it is
inexplicably intertwined with consciousness and introspection. Here I suggest we rethink this
definition based on criteria that can be externally verified and objectively evaluated.
Keywords: episodic memory, nonhuman animals, recollection, hippocampus
Most of us can think back to the previous week (e.g., a recent
dinner with friends) and events of importance (e.g., moving to a
new place) without much difficulty. Can nonhuman animals en-
gage in similar behaviour? By the current definition of episodic
memory, this inability to peer into the introspective behaviours of
nonhuman animals means we can only ascribe evidence of
“episodic-like” memory to them. This approach seems overly
limited and anthropocentric. Here I suggest that we shift toward
more objective criteria for defining episodic memory that do not
rely on introspection or necessitate conscious recollection. The
implications of this rethinking are discussed, as well as consider-
ations of familiarity, indirect measures of memory, and generally
what should be viewed as necessary for episodic memory. Epi-
sodic memory is studied in a variety of subfields within psychol-
ogy, including cognitive psychology, neuropsychology, and cog-
nitive neuroscience, in addition to comparative psychology. In this
article, I draw from converging evidence from all of these sub-
fields to suggest a path forward that may be consistently and
broadly used. By adopting a new definition that can be externally
verified, objectively evaluated, and less reliant on self-report,
episodic memory can be more consistently assessed across a
variety of subfields. This perspective is intended to begin an
iterative process within the field to redefine the meaning of epi-
sodic memory and to ultimately establish a consensus view.
The current definition of episodic memory, as described in
(Tulving, 2002), includes a rich characterisation of the concept:
Episodic memory is a recently evolved, late-developing, and early
deteriorating past-oriented memory system, more vulnerable than
other memory systems to neuronal dysfunction, and probably unique
to humans. It makes possible mental time travel through subjective
time, from the present to the past, thus allowing one to reexperience,
through autonoetic awareness, one’s own previous experiences. Its
operations require, but go beyond, the semantic memory system.
Retrieving information from episodic memory (remembering or con-
scious recollection) is contingent on the establishment of a special
mental set, dubbed episodic “retrieval mode.” Episodic memory is
subserved by a widely distributed network of cortical and subcortical
brain regions that overlaps with but also extends beyond the networks
subserving other memory systems. The essence of episodic memory
lies in the conjunction of three concepts: self, autonoetic awareness,
and subjectively sensed time. (p. 5)
Critically, Tulving drew a direct and unambiguous correspon-
dence between systems of memory (episodic, semantic, and pro-
cedural) and the involvement of consciousness, with episodic
memory corresponding to autonoetic (self-knowing) conscious-
ness. Based on this definition, often it is suggested that animals
have “episodic-like memory,” rather than episodic memory itself,
The author thanks Daniela Palombo for insightful discussions that
helped refine the ideas presented in this article.
Correspondence concerning this article should be addressed to XChristopher
R. Madan, School of Psychology, University of Nottingham, Nottingham NG7
2RD, United Kingdom. E-mail: christopher.madan@nottingham.ac.uk
Canadian Journal of Experimental Psychology /
Revue canadienne de psychologie expérimentale
ISSN: 1196-1961 2020, Vol. 74, No. 3, 183–192
© 2020 Canadian Psychological Association http://dx.doi.org/10.1037/cep0000229
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