Episodic memory

Episodic memory is a system of memory that is concerned with the encoding, storage, and retrieval of discrete past events. It is autobiographical in nature, meaning that it involves an individual’s own experiences and perceptions of what happened where and when, as well as one’s consciousness of remembering and subjective sense of time. Episodic memory is often contrasted with semantic memory, the knowledge of objective facts, and procedural memory, the knowledge of how to do something.

Because one’s sense of self is based in large part on the memory of past life experiences, episodic memory has been the subject of philosophers as well as psychologists and neuroscientists who are interested in the basic questions of human existence: who we are, and why we are the way we are. Scientists also study episodic memory and other types of memory systems to further our understanding of how the brain works. Studies of how episodic memory is formed, retained, and retrieved may help researchers develop treatments for conditions that involve either memory loss, such as Alzheimer’s disease and dementia, or memories of traumatic events, such as post-traumatic stress disorder.

Overview

Estonian Canadian psychologist and neuroscientist Endel Tulving first distinguished episodic memory from semantic memory in 1972 in “Episodic and Semantic Memory,” a chapter in Organization of Memory, which he edited with Wayne Donaldson. At the time, Tulving wrote that he was making the distinction in order to facilitate discussion, not because he necessarily believed that the two systems were structurally or functionally separate.

According to Tulving, episodic and semantic memory differ in terms of the nature of the information they store, whether the reference is autobiographical or cognitive, the conditions and consequences of retrieval, how much they depend on each other, and their susceptibility to transformation and erasure of stored information by interference. Episodic memory is concerned with information about distinct episodes, events that have occurred at a specific time and place, as well as the time-space relationships between such events. Furthermore, episodic memory is autobiographical and perceptual, as opposed to cognitive; it refers to events that an individual has personally experienced or perceived, rather than general knowledge and facts.

Tulving theorized that episodic memory is vulnerable to transformation and loss of information because the act of remembering an episodic memory itself changes the contents of the memory. He also thought that while the registration of an event in the episodic memory can sometimes be influenced by information in one’s semantic memory, the episodic memory is capable of operating independently of semantic memory.

Tulving further expounded on episodic and semantic memory in his much-cited 1983 book Elements of Episodic Memory. In this work, he asserts, among other things, the then-controversial theory that episodic memory and semantic memory are functionally distinct. Since then, neuroimaging models have shown that episodic memory retrieval and semantic memory retrieval involve different parts of the brain.

Bibliography

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Baddeley, Alan, Martin Conway, and John Aggleton, eds. Episodic Memory: New Directions in Research. Oxford: Oxford UP, 2002. Print.

Berntsen, Dorthe, Søren Risløv Staugaard, and Louise Maria Torp Sørensen. “Why Am I Remembering This Now? Predicting the Occurrence of Involuntary (Spontaneous) Episodic Memories.” Journal of Experimental Psychology: General 142.2 (2013): 426–44. Print.

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Miller, Greg. “Making Memories.” Smithsonian May 2010: 38–45. Print.

Tulving, Endel. Elements of Episodic Memory. 1983. Oxford: Oxford UP, 2008. Print.

Tulving, Endel. “Episodic and Semantic Memory.” Organization of Memory. Ed. Tulving and Wayne Donaldson. New York: Academic, 1972. 381–403. Print.

Tulving, Endel. “Episodic Memory: From Mind to Brain.” Annual Review of Psychology 53 (2002): 1–25. Print.

Weisberg, Robert W., and Lauretta M. Reeves. Cognition: From Memory to Creativity. Hoboken: Wiley, 2013. Print.

Wichert, Sonja, Oliver T. Wolf, and Lars Schwabe. “Updating of Episodic Memories Depends on the Strength of New Learning after Memory Reactivation.” Behavioral Neuroscience 127.3 (2013): 331–38. Print.