Episodic memory constitutes a personal diary of things that have happened to you—everything from memories of what you did on your last birthday to the unique experiences you had on your first day at high school.
Definition and Overview
Episodic memory is a component of the declarative system of long-term memory and refers to the ability to consciously recollect events and episodes, with specific information about the time and space constraints in which these events occurred.
Episodic memory is also currently described as the memory system in charge of the encoding, storage, and retrieval of personally experienced events, associated with a precise spatial and temporal context of encoding.
Episodic memory allows the conscious recollection of happenings and events from one’s personal past and the mental projection of anticipated events into one’s subjective future.
Recollection of episodic events includes autonoetic awareness, which is the impression of re-experiencing or reliving the past and mentally traveling back in subjective time.
The defining property of the experience of episodic memory is that it involves mental time travel.
When we are having an episodic memory we are traveling back in time to reconnect with events that happened in the past.
For example, I can travel back in my mind to 1996 to remember cresting the top of a mountain near the California coast for the first time and seeing the Pacific Ocean far below, stretching into the distance. I remember sitting in the car, seeing the ocean, saying “Wow!” to my wife who was sitting next to me, and some of the emotions I was experiencing.
This type of memory is sometimes referred to as autobiographical memory Opens in new window, because it always involves the presence of the self (Brewer, 1986).
It always pertains to things that happened in the presence of the rememberer.
Tulving describes this experience of episodic memory as self-knowing or remembering, with the idea that remembering always involves mental time travel.
Note, however, that putting oneself back in a situation through mental time travel does not guarantee that the memory is accurate.
Episodic memories are created very quickly. Time and especially place are the organizational principles of this type of memory, which means that, at least initially, episodic memories are recalled in a particular temporal or spatial order.
Much of our everyday conscious remembering is of episodic memories, and it is such memories we are referring to when we speak of our memories.
The memory disorder commonly referred to as amnesia Opens in new window is usually a loss of episodic memories. Amnesiacs usually retain their general knowledge, but lose memories of personal situations related to the self.
Again, putting oneself back in a situation through mental time travel does not guarantee that the memory is accurate, as originally experienced.
This is so because episodic memories seem highly susceptible to distortion, especially with repeated recollection. Thus, when we repeatedly recollect specific episodic memories, they are changed by the very process of recollection.
This may be because recalling an episodic memory is itself an episode that becomes remembered, and this copy of the memory replaces the original.
There is, after all, no way distinguish between a memory, and a memory of a memory.
Remembering an episodic memory might then be conceptualized as a kind of selective rehearsal, during which various details get amplified or suppressed, usually in relation to the value systems and schemas of the rememberer.
Episodic memories appear to interact dynamically with our values models, categories, and so on, all of which have a bearing on how we represent things to ourselves. What we remember thus interacts dynamically with what we know feel, and want.
Episodic memories are not constructed from scratch or entirely from experience, but at least partly from knowledge categories (semantic memories) already formed by many previous experiences (D’Andrade, 1995: 189). This means that semantic and episodic memory are somewhat interdependent.
Our categories enable us to deal with the enormous amount of information in even the blandest experience, to stabilize or anchor our memories, and indeed to make sense of our experience at all.
The details of episodic memories generally become integrated with our categories Opens in new window. Episodic memories are usually constructed within a framework of pre-existing memory.
These categories Opens in new window are thought to be formed around protypes, or best examples of things (Lakoff, 1987). All of which means that our memories of the specific aspects of situations are often not very reliable, especially if they have been recalled repeatedly.
For example, say that on listening to a recording of a particular piece of music, I categorize a section in the piece as “loud” or “fast.” If I listen to the piece again at a later time, it is possible and even likely that I will be surprised that the section is not as “loud” or “fast” as I remembered it to be.
This will be especially likely if I have thought about the music between listenings, without actually hearing it again.
The actual episodic memory of the experience has been “colored” by my categorization of it. Indeed, some theorists (e.g., Edelman, 1989: 109–118) would say that my memory of the experience is my categorization Opens in new window of it.
In this way, an episodic memory is somewhat like a caricature of an experience, an example of how much the initial categorization (coding) of an experience shapes the memory of that experience.
The basic categorical units used in the construction of episodic memory are probably not very large. It is thought that these types of memories are stored as individual, relatively low-level features.
The features are then recombined in various patterns (chunks) to form specific episodic recollections. The same feature may well be incorporated in many different memories.
Over time, these features may recombine in different ways, and even features from different episodes may combine. (This type of confabulation of features happens regularly in dreams.)