Mental Time Travel

Episodic memory is the phenomenon of being able to recall experiences in the past. Some have descriptively dubbed it “mental time travel”. Episodic memory is different from all other memory systems because it takes place in the past, built by the what, when, and where of personal experience rather than what is known or learned. Episodic memory is essentially the storage of information about what happened at a particular place at a particular time. Endel Tulving coined the term in 1972. Decades later researchers are still attempting to understand it as a neurocognitive entity.

Autonoetic consciousness

Tulving addressed the phenomenon and what was learned in the 30 years after his initial discovery in Annual Reviews. Researchers had found that episodic memory focuses not only on tasks, but on the sense of self, including perceptions of time and how the experience relates to oneself (self-awareness and consciousness). Episodic memory does not confuse the past with the present, but it is clearly delineated in one’s thoughts. The term given this awareness is autonoetic. Thus, episodic memory is unique to each individual person – “self” is needed to define it. For example:  conscious recall of “Did I shut off the stove?”, unconscious recall of where you met someone before.

Mind vs. brain

Episodic memory was once thought to be psychological in nature – of the mind. But the memories are clearly stored in the brain (neurocognitive). Though originally thought to be competitive with semantic memory, the retrieval of facts, 2005 research found that they can be modified separately. This indicates that they are two, co-existing forms of memory retrieval in the brain. In other words, remembering consists of a combination of various forms of information stored in the brain.

Being able to retrieve an episodic memory requires a special mental set called episodic retrieval mode. The network for episodic memory extends farther through the cortical and subcortical regions of the brain than the semantic memory network. The actual phenomenon is not easily measured because it is not a specific task – it iss a “hypothetical memory system” according to Tulving. It is intangible, though characteristics of the system can be measured.

Episodic memory in humans

Tulving states that the phenomenon of episodic memory was a recently evolved trait, unique to humans and evolving from semantic memory. It is also a system that develops late and deteriorates early. Differences have been found between how episodic memory works in children and adults. Also, alcohol dependence has been shown to damage both episodic memory and awareness of memory. ScienceDaily summarized a study from 2010 that found inhibited metamemory (the ability to process, store and retrieve information) in those suffering from alcohol dependence; alcoholics overestimated their ability to remember. Dysfunction of episodic memory is also clear in Alzheimer’s patients and others suffering from memory-related dementia.