Explicit memory is the conscious, intentional recollection of previous experiences and information. This information is about a specific event that has occurred at a specific time and place, both in your personal life and in the world at large. Examples of explicit memory can be turning on your computer this morning and editing an article in Wikipedia, or the 1974 Eurovision Song Contest.
Explicit memory involves conscious recollection, compared with implicit memory which is an unconscious, nonintentional form of memory. Remembering a specific driving lesson is an example of explicit memory, while improving your driving skills during the lesson is an example of implicit memory.
Encoding and retrieval of explicit memory
Encoding: Explicit memory depends on conceptually driven, top-down processing, in which a subject reorganizes the data to store it. The subject makes associations with previously related stimuli or experiences. The later recall of information is thus greatly influenced by the way in which the information was originally processed.
The depth-of-processing effect is the improvement in subsequent recall of an object about which a person has given thought to its meaning or shape.
Simply put: To create explicit memories, you have to do something with your experiences: think about them, talk about them, write them down, study them, etc. The more you do, the better you will remember.
Retrieval: Because a person has played an active role in processing explicit information, the internal cues that were used in processing it, can also be used to initiate spontaneous recall.
Simply put: When you've talked about a certain experience, the words that you used, will help you when you half a year later try to remember this experience.
Neural structures involved in explicit memory
Several neural structures are proposed to be involved in explicit memory. Most are in the temporal lobe or closely related to it, such as the amygdala, the hippocampus, the rhinal cortex in the temporal lobe, and the prefrontal cortex.
Nuclei in the thalamus also are included, because many connections between the prefrontal cortex and temporal cortex are made through the thalamus.
The regions that make up the explicit memory circuit receive input from the neocortex and from brainstem systems, including acetylcholine, serotonin, and noradrenaline systems.
Two kinds of explicit memory
Episodic memory, also called autobiographical memory, consists of the recollection of singular events in the life of a person. It is the memory of life experiences centered on yourself.
Episodic memory is necessary for "time traveling": remembering your past and imagining your future. It is considered a uniquely human quality that depends on maturaton and therefore won't be found in babies and young children.
Semantic memory consists of all explicit memory that is not autobiographical. Examples of semantic memory is knowledge of historical events and figures; the ability to recognize friends and acquaintances; and information learned in school, such as specialized vocabularies and reading, writing and mathematics.
The neural basis of episodic and semantic memory is not yet known today. However, some scientists suggest that episodic memory might be dependent on the right hemisphere, and semantic memory on the left hemisphere.
Kolb & Whishaw: Fundamentals of Human Neuropsychology (2003), chapter 18
- H.L. Petri and M. Mishkin: Behaviorism, cognitivism, and the neuropsychology of memory, in: American scientist, 82:30-37, 1994
- E. Tulving: Episodic memory: from mind to brain. In: Annual review of psychology 53:1-25, 2002.
- These scientists are E. Tulving and R.F. Thompson