Episodic v. Autobiographical Memory Determining

Episodic v. Autobiographical Memory

Determining the Difference Between Episodic and Autobiographical Memory

Memory is one of the most easily observable and yet most complex and misunderstood of the workings of the human brain. It is also one of the most essential functions that the brain serves; without the ability to form and retrieve memories, human beings would not have the ability to process and use any sort of information or do anything that required any sort of conscious planning. For that reason, the various physical and psychological mechanisms in the brain that allow for the formation, processing, and the retrieval of memories has been a subject of increasing interest to psychologists, neurobiologists, and other scientific researchers. Being able to explain memory can go a long way in helping us to understand the way we think, which would enable better leanring environments.

One of the recent continuing debates in the scientific community concerning memory in human beings is the difference, if any, between autobiographical and episodic memory. The problem starts out as one of definition; As Tulving (1972) notes, one of the hallmarks of a developing science is the "looseness of [its] definition[s]," and for some time the definitions of autobiographical and episodic memory were synonymous, necessarily meaning that the two different labels for memory referred to the same thing. Emerging evidence suggests, however, that there are two separate mechanisms at work producing two different types of memory (and not the only two, it should be noted) that should be referred to separately as autobiographical memory -- that which generally deals with events and information from a person's life and experience -- and episodic memory, which organizes events and information into temporal locations. A careful examination of the current literature is convincing in making this delineation.

Tulving (1972) defines episodic memory quite broadly as that mechanism or type of memory that "receives and stores information about temporally dated episodes or events, and temporal-spatial relations among these events" (p. 385). To him, this makes autobiographical memory a mere subset of episodic memory; all episodic memory must relate to the person's past experience, and so is necessarily autobiographical (Tulving 1972). Flash-bulb memories are one example that seems to confirm the belief in the synonymous nature of autobiographical memory and episodic memory. These are memories that are formed during hugely important and usually surprising events -- the sudden death of a parent, child, or spouse, the Kennedy assassination, and the September 11 terrorist attacks are all examples of events that typically form flash-bulb memories, in which the individual can usually recall with incredible detail the visual and auditory input surrounding them when they first heard of the event.

Flash-bulb memories place autobiographical memories into very distinct temporal-spatial relationships, seeming to confirm Tulving's assertions. Interestingly, the two type sof memory also seem to coincide with the phenomenon of false memory. Many individuals "remember" things incorrectly, or often remember as personal incidents things that happened to others or that were merely imagined (Summerfield et al. 2009). During MRI scans, research participants were asked to recall events that had actually happened to them, that they had witnessed on a film, or that they had previously imagined, and the same areas of the brain became active in all of these memory retrievals (Summerfield et al. 2009). The fact that there was additional activity for real autobiographical events only further strengthens the link between episodic and autobiographical memory.

Episodic memory would be capable of processing fictive events as well as real ones, and the fact that both real and imagined memories trigger the same areas of the brain -- with autobiographical memories creating some additional activity), could be (and has been) interpreted as meaning that autobiographical memory is merely a type or subset of episodic memory (Summerfield et al. 2009). In a somewhat similar study, Svoboda & Levine (2009) tested regions of the brain for rehearsed and unrehearsed memories, and found that episodic and autobiographic memories reacted quite similarly to repetition and rehearsed retrieval, but quite differently than semantic memories. They located episodic autobiographical memory (considered a single type by the researchers) in the hippocampus, concluding that "there is strong evidence that the hippocampus is centrally involved in binding of disparate elements for recollection," making it the essential center for both types of memory (Svoboda & Levine 2009).

There is an abundance of other research, however, that suggests that while two mechanisms and types of memory may coincide quite often, they are in fact two separate phenomena, and will only be truly understood when seen as such. In a careful review of past neuroimaging studies, Gilboa (2004) noted distinct differences in prefrontal cortex activation in test of the two types of memory, suggesting "that care and caution should be exercised in extrapolating from the way we recollect 'events' from a list learned in the laboratory to the way we recollect events from our lives" (p. 1336). In an even more compelling study, it was found that patients with frontal cortical excisions showed no impairment in autobiographical memory retrieval, but were far less likely to organize events temporally (Thaiss & Petrides 2008).

These studies strongly suggest that there are different physical and neurological mechanisms at work in the brain in the formation and retrieval of episodic memory and autobiographical memory. It should not be surprising that other studies note the activation of similar and even identical portions of the brain in the creation and accessing of both types of memory; as noted earlier, the two types of memory will necessarily coincide quite often given the similarities of their function. Even here, tough, there are significant differences. Martin Conway (2002) notes that "autobiographical knowledge [or memory]...place[s] constraints on what goals the self can realistically maintain and pursue" (p. 55). Episodic memory, however, is not so self-referentially motivated; previously mentioned studies have shown its capability of storing and sorting impersonal and even fictive memories (Summerfield et al. 2009; Svoboda & Levine 2009).

In their exhaustive review and analysis of published literature on the subject, Andrew Mayes and Neil Roberts (2001) detail many of the physical structures and processes in the brain theorized to be involved in the formation and retrieval of episodic memory. The intricate processing of episodic memory could possibly be where the divergence of autobiographical memory can be seen; the many different portions of the brain identified in processing separate aspects of memory shows a clear differentiation in the creation of temporal relationships between memories and the actual visual memory that is most quickly and easily recalled (Mayes & Roberts 2001). Thus, some episodic memories may be autobiographical, but the two are distinct.