Most people today have heard of short term memory and long term memory. We commonly think information goes into our short term memory and if we are lucky it “sticks” and goes into our long term memory.
However, in order for information to be stored and be retrievable it actually has to go through a sequence of 3 stages: sensory memory, short term memory (also known as working memory), and then long term memory.
The sensory stage generally lasts less than a second, short term is approximately a minute or less, and then long term memory is capable of lasting a lifetime.
Long term memory can be further divided into either explicit memory or implicit memory. The terms “explicit memory” and “implicit memory” were first used by Graf and Schacter (1985) and have been widely used since that time.
Although there has been considerable debate, research over the years has generally supported the two distinct systems.
What is Explicit Memory?
Explicit memory is the storage of facts and events, information from the external world that is explicitly stored and retrieved. It takes a conscious, intentional effort on the person’s part to conjure up these facts and events.
In order to form and store explicit memories, it is necessary to use associations to previous related experiences or knowledge. Therefore, it is not found in babies or young children as it relies on previous experience/knowledge which only occurs through maturation.
It is often thought of as information learned in school although realistically it is learned throughout the day, throughout a lifetime.
Explicit memory is utilized throughout the day, such as remembering the time of a doctor’s appointment or recalling an event from last week or several years ago.
It consists of knowledge of historical events and figures, the ability to recognize others, academic abilities, as well as autobiographical memories such as events that happen to, or around, that person.
It is also known in the literature as “declarative memory” as you can declare or easily verbalize the recollected information. Explicit memory can be thought of as knowing what (rather than knowing how).
Let’s take the example of driving a car.
After lots of experience, remembering how to drive a car becomes automatic – which is an implicit memory.
However, recalling who taught you to drive and what make of automobile your first car was are examples of explicit memories.
What is Implicit Memory?
Implicit memory, on the other hand, is the unconscious memory of skills and how to do things. It is knowing how.
Implicit memories relate especially to the use of objects or movements of the body such as riding a bike, catching a ball, brushing your teeth or playing a piano.
It is sometimes called “procedural memory” as these motor memories allow us to carry out motor actions automatically. It consists of automatic sensorimotor procedures that are so deeply embedded that we are no longer conscious (we have no explicit awareness) of the individual actions required to carry out that process.
The literature indicates that implicit memory is present at birth and it is less pervious to age-related changes or damage from diseases like Alzheimer’s. These forms of memory are still usable even after organic brain damage such as Alzheimer’s because they do not require conscious executive functioning; in other words, you don’t have to think about it.
This helps explain why elderly people are more capable when they stay in a place they are familiar with; if you place that same individual in an unfamiliar place they will no longer have the implicit memories, the automatic routines, that they were able to utilize in their familiar environment and may make the elderly person appear significantly more impaired.
Implicit memory occurs at an unconscious level all day long. As you go about your day, you absorb information from your environment without thinking about it.
You don’t make conscious decisions to remember everything around you and yet when you need an object, for example, you are often able to visualize and recall where you last saw it.
How do Explicit Memory and Implicit Memory Differ?
These two types of long term memory are fundamentally different in processing as well as where they are stored in the brain.
Explicit memories are easily verbalized and require a conscious recollection in order to recall something whereas implicit memories lack conscious awareness. Explicit memories are considered more complex as they are comprised of a variety of aspects in a given situation.
For example, if you want to recall a meeting from last week, you will recall the event as well as the context around it such as the time of day, place, objects and people that were present.
Explicit memories appear to be encoded in the medial temporal lobe of the brain (hippocampus, entorhinal cortex and perirhinal cortex) but stored in the temporal cortex.
Implicit memories are encoded and stored by the cerebellum (and putamen, caudate nucleus and motor cortex depending on the type of activity).
Interestingly, explicit and implicit memories are utilized differently at divergent points in a person’s life.
For example, a child under the age of 7 tends to learn a new language easily, without much thought, using the implicit memory system. Adults use the explicit memory system to learn the rules and vocabulary of the new language, most often with greater effort.
As a person ages, explicit memory skills tend to decline yet implicit memory skills often remain intact.
Studies using patients with amnesia or Alzheimer’s have shown that it is possible to have a fully functioning implicit memory system despite having a significantly impaired explicit memory system.
- Graf,P. & Schacter,D.L. (1985). Implicit and explicit memory for new associations in normal and amnesic subjects. Journal of Experimental Psychology: Learning memory and Cognition, 11, 501-518
- Newcombe, Nora S.; Lloyd, Marianne E.; Ratliff, Kristin R., Kail, Robert V. (Ed), (2007). Advances in child development and behavior (Vol 35). Advances in child development and behavior. Vol 35, (pp. 37-85). San Diego, CA, US: Elsevier Academic Press, xi, 414 pp.