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Episodic memory is a type of long-term, declarative memory that involves the recollection of personal experiences or events, including the time and place they occurred. It allows you to travel back in time to relive past experiences, like remembering your first day at school.
Take-Home Messages
- Episodic memory is part of long-term explicit memory, and comprises a person’s unique recollection of experiences, events, and situations. Episodic memories usually include details of an event, the context in which the event took place, and emotions associated with the event. It involves conscious thought and is declarative.
- Your memories of your first day of school, what you have for breakfast, and your graduation are all examples of episodic memories. Episodic memory is important as it helps individuals construct a sense of self.
- The Canadian psychologist Endel Tulving first introduced the term ‘episodic memory’ to distinguish ‘remembering’ from ‘knowing.’
- While episodic memory involves a person’s autobiographical experiences and associated events, semantic memory involves facts, ideas, and concepts acquired over time.
- Specific events, general events, personal facts, and flashbulb memories constitute different types of episodic memory.
Episodic memory, which is a part of long-term explicit memory, comprises each person’s unique recollection of specific experiences, events and situations (Schacter, Gilbert & Wegner, 2009). Generally, emotions associated with a memory tend to raise the likelihood that that memory would be recollected more easily and more vividly (McCloskey, Wible & Cohen, 1988).
Origin
The term ‘episodic memory’ was first introduced in 1972 by the Canadian experimental psychologist Endel Tulving. He used the term to describe the difference between ‘remembering’ and ‘knowing.’
Tulving (1972) identified remembering as a feeling associated with the past (and therefore episodic), and knowing as recalling facts (and therefore semantic).
Additionally, Tulving (1985, 2002) pointed out that mental time travel, connection to self, and autonoetic consciousness were the three main properties of episodic memory.
Examples
- An example of an episodic memory is recalling your first kiss.
- Recalling what you did over the Christmas holidays.
- Remembering your first day at school.
- Recalling what you had for breakfast this morning.
- Remembering a family vacation, like a trip to the beach or a visit to a theme park.
- Recalling the moment when you received your university acceptance letter.
- Remembering the details of a movie you watched last week.
- Recalling your wedding day or another significant life event.
- Remembering a funny incident that happened at a party last month.
- Recalling a conversation you had with a friend recently.
Types of Episodic Memory
Individuals may have different types of episodic memories as follows:
Autobiographical Memory
A special form of episodic memory is autobiographical memory, which includes individuals’ recollections of their own life experiences. This type of memory incorporates semantic and episodic memory elements, connecting personal experiences to specific times and places throughout an individual’s life.
Specific events involve the recollection of particular moments from an individual’s autobiographical history. Recalling the first time you dove into the ocean is an example.
In the episodic memory system, information about specific events is tied to the situational context in which they occurred. The individual remembers information about the event (“what”) and its context of occurrence (e.g., “where” or “when” it happened).
General Events
General events involve recalling the feelings associated with a certain type of experience. In general, recalling what it is like to dive into the ocean is an example of this type of episodic memory.
You may not remember each occasion wherein you dove into the ocean. But you do have a general recollection of having dived many times into the ocean—upon which your feeling is based.
Personal Facts
Information intricately tied to a person’s experiences constitute personal facts. Knowing the color of your first bicycle and the name of your first dog are some examples.
Flashbulb Memories
Flashbulb memories are exceptionally vivid and highly detailed ‘snapshots’ of moments or circumstances wherein you learned important or surprising pieces of news (Brown & Kulik, 1977).
Recalling the moment you heard about the death of a family member or a major tragedy such as the 9/11 attacks might be an example.
It should be noted that there is much debate as to whether the vividness of a flashbulb memory stems from a virtual flash produced by the emotional intensity of a specific experience or from a propensity to rehearse consequential moments—which can immensely strengthen the memory.
Episodic Memory vs. Semantic Memory
Episodic and semantic memory are types of long-term memory known as explicit or declarative memory.
Episodic memory stores information relating to episodes in a person’s life, such as childhood experiences. Semantic memory is responsible for storing factual knowledge about the world.
Semantic memory contains general knowledge that is not tied to the time when the information was learned, such as general knowledge, facts, rules, and ideas. Episodic memory is made up of chronologically or temporally dated recollections of personal experiences.
There is also evidence for the different types of long-term memory from brain scans. For example, Tulving (1989) showed that when episodic memory is used, the frontal lobes are activated, but when semantic memory is used, the back of the cerebral cortex is active.
The Related Brain Structures
The medial temporal lobe, which includes the hippocampus and the right hemisphere of the prefrontal cortex, plays a vital role in the formation of new episodic memories (Janowsky, Shimamura & Squire, 1989).
Some research suggests that the prefrontal cortex employs its executive function to aid the more efficient storage of information (Gabrieli, Poldrack & Desmond, 1998). Other evidence, however, implies that the inferior parietal lobe enhances the perceived oldness or the vividness of an experience (Berryhill, Picasso, Phuong, Cabeza & Olson, 2007).
Additionally, some experts hold that episodic memories permanently depend upon the hippocampus (Deisseroth, Singla, Toda, Monje, Palmer & Malenka, 2004).
Others, nonetheless, contend that episodic memories are stored in the hippocampus only for a short time. The latter group holds that these memories, following a brief period in the hippocampus, are consolidated in the neocortex. This opinion is supported by recent evidence on neurogenesis in the hippocampus, which sheds light on the removal and formation of memories.
Moreover, episodic memory seems to emerge when a child is 3 or 4 years of age (Scarf, Gross, Colombo & Hayne, 2013). Nonetheless, the activation of certain brain regions, such as the hippocampus, seems to differ among adults.
While older individuals (aged 67-80) seem to activate both the right and the left hippocampus, younger individuals (aged 23-39) do not activate the right hippocampus (Maguire & Frith, 2003).
Neural Networks
It is possible to store episodic memories in auto-associative neural networks provided that the representation of the stored memories contains information about the spatiotemporal context wherein the representation was examined (Khalil, Moftah & Moustafa, 2017).
Neural networks, which enhance the comprehension of the transmission and the reception of various messages to and from the body, comprise interconnected structures or neurons which harmoniously produce different intra-brain cognitions (Henderson, 2012).
Additionally, these networks can contract or expand based on the type of information being processed at a given time (Nestor, Kubicki, Gurrera, Niznikiewicz, Frumin, McCarley & Shenton, 2004).
References
Berryhill, M. E., Phuong, L., Picasso, L., Cabeza, R., & Olson, I. R. (2007). Parietal lobe and episodic memory: bilateral damage causes impaired free recall of autobiographical memory. Journal of Neuroscience, 27 (52), 14415-14423.
Brown, R., & Kulik, J. (1977). Flashbulb memories. Cognition, 5 (1), 73–99.
Clayton, N. S., Salwiczek, L. H., & Dickinson, A. (2007). Episodic memory. Current biology: CB, 17 (6), R189–R191.
Deisseroth, K., Singla, S., Toda, H., Monje, M., Palmer, T. D., & Malenka, R. C. (2004). Excitation-neurogenesis coupling in adult neural stem/progenitor cells. Neuron, 42 (4), 535–552.
Gabrieli, J. D., Poldrack, R. A., & Desmond, J. E. (1998). The role of left prefrontal cortex in language and memory. Proceedings of the national Academy of Sciences, 95 (3), 906-913.
Henderson, J. M. (2012). “Connectomic surgery”: diffusion tensor imaging (DTI) tractography as a targeting modality for surgical modulation of neural networks. Frontiers in integrative neuroscience, 6, 15.
Howard, M. W., & Kahana, M. J. (2002). When does semantic similarity help episodic retrieval? Journal of Memory and Language, 46 (1), 85-98.
Janowsky, J. S., Shimamura, A. P., & Squire, L. R. (1989). Source memory impairment in patients with frontal lobe lesions. Neuropsychologia, 27(8), 1043-1056.
Khalil, R., Moftah, M. Z., & Moustafa, A. A. (2017). The effects of dynamical synapses on firing rate activity: a spiking neural network model. European Journal of Neuroscience, 46 (9), 2445-2470.
Maguire, E. A., & Frith, C. D. (2003). Aging affects the engagement of the hippocampus during autobiographical memory retrieval. Brain, 126 (7), 1511-1523.
McCloskey, M., Wible, C. G., & Cohen, N. J. (1988). Is there a special flashbulb-memory mechanism?. Journal of Experimental Psychology: General, 117 (2), 171.
Nestor, P. G., Kubicki, M., Gurrera, R. J., Niznikiewicz, M., Frumin, M., McCarley, R. W., & Shenton, M. E. (2004). Neuropsychological correlates of diffusion tensor imaging in schizophrenia. Neuropsychology, 18 (4), 629.
Scarf, D., Gross, J., Colombo, M., & Hayne, H. (2013). To have and to hold: Episodic memory in 3‐and 4‐year‐old children. Developmental psychobiology, 55( 2), 125-132.
Tulving, E. (1985). Memory and consciousness. Canadian Psychology, 26 (1), 1.
Tulving, E. (1983). Elements of Episodic Memory. London: Oxford University Press.
Tulving, E. (1989). Remembering and knowing the past. American Scientist, 77 (4), 361-367.
Tulving, E., & Markowitsch, H. J. (1998). Episodic and declarative memory: role of the hippocampus. Hippocampus, 8(3), 198-204.
Tulving, E. (2002). Chronesthesia: Conscious awareness of subjective time.
