Most times when we think about forgetting, we may think of the time we forgot someone’s name, forgot an answer to a test, or forgot the location of a friend’s house. These examples are common errors of restrospective memory (being memory for past events).
Consider the opposite scenario, of which some people may think about forgetting Opens in new window, and lament their ‘to-do list’ items that went unchecked, such as forgetting to buy a card for a family member’s birthday, forgetting to order a medication refill, or forgetting an approaching deadline for a writing assignment.
When someone fails to remember to perform such intended actions in the future, they are experiencing an impairment of prospective memory (Einstein and McDaniel, 2005).
What Is Prospective Memory?
Prospective memory is memory for remembering any intended action that must be completed at a particular moment in the future. It includes remembering a plan of action (i.e. to do something) and also remembering to do it.
Prospective memory consists in the ability to plan an action and remember to perform it at some point in the future. This implies the subject hold the intention in mind from the time s/he forms it to the time s/he translates it into action.
Prospective memory is almost continuously active in everyday scenarios because many actions involve long-range planning. We go through the day employing prospective memory to remember:
- to pay the gas bill;
- to phone a relative;
- to give your house-mate the message that a friend called;
- to buy more pet food;
- to raise a point at a meeting;
- to look up a reference in the library;
- to pick up bread at the mall on your way home, and so on.
Prospective memory depends on stores of episodic and semantic memory. Holding and retrieving this information is necessary to form and complete actions plans.
Types of Prospective Memory
Prospective memory is necessary to sustain an intention in an ongoing of future task. This allows one to form and hold an intention about a future action until the time when one executes the intention in the action.
Although there are numerous forms of prospective memory Opens in new window, only two types are commonly researched. These are, event-based - and time-based prospective memory.
- Event-based prospective memory consists in remembering to perform an action when a specific external event occurs, such as giving a certain person a message.
- Time-based prospective memory involves remembering to perform an action at a particular time (or a fixed amount of time), such as pressing a key every 8 minutes, or at a fixed point in time, such as remembering an appointment at 1 P.M.
Both types of prospective memory depend on retrospective stores of episodic Opens in new window and semantic memory Opens in new window. Dysfunction in any of these regions can impair the capacity to recall earlier intentions and result in failure to perform actions.
Consider a parent who leaves a child unattended in a car but has an intention to return to the car within a brief period. This involves an episodic memory of leaving the child in the car, an intention to return to return to the car and a memory of forming that intention.
By returning to the car and the child within this period, the parent demonstrates that she held the intention throughout this period and translated it into the appropriate action. She successfully demonstrated prospective memory. However, if she failed to return to the car within the critical period, then she failed to hold and act on the intention and thus demonstrated prospective memory failure.
Again, suppose that a researcher is giving a 30-minute presentation on a particular topic. In the introduction, he says that he will discuss a controversial hypothesis toward the end of the presentation.
Discussing it would demonstrate successful exercise of prospective semantic memory regarding facts and concepts. His ability to execute his intention to discuss the issue requires forming and retaining a memory of the intention. If he failed to discuss the issue after announcing that he would, then his prospective memory would have failed. He would have forgotten his intention.
Retrospective episodic and semantic memory systems allow individuals to recognize triggering or target cues in the environment that enable them to hold the intention and execute it in the appropriate place and at the appropriate time. Holding and retrieving this information is necessary to form and complete actions plans (McDaniel, Umanath, Epstein et al., 2015).
Relationship between Prospective and Retrospective memory
A major point of interest is the relationship between prospective and retrospective memory. The rate at which items are recalled in retrospective memory Opens in new window is roughly the same in prospective memory. This implies that the same neurobiological mechanism underlies both types.
Baddeley and Wilkins (1984) have pointed out that, in practice, the distinction between the two kinds of memory is not absolutely clear-cut because prospective memory necessarily includes some elements of retrospective memory.
For example, in remembering my plan to phone my mother, I also remember, retrospectively, her number and how to use the phone, and not to call while she is watching her favorite television program.
However, despite this overlap between the two kinds of memory, there are numerous distinguishing features (West, 1984).
Prospective memory differs from retrospective memory at the encoding stage, as prospective plans are usually self-generated and do not involve initial learning, but the difference between the two is perhaps more marked at the retrieval stage.
In prospective memory, the amount of information that has to be remembered is usually small. You need only remember to post the letter, call the plumber, or whatever.
In most retrospective memory tasks the amount of information that has to be recalled is much greater. Some studies have also shown that prospective memory ability and retrospective memory ability show signs of dissociation.
Basically, prospective memory involves remembering that something needs to be done. However, retrospective memory supports remembering what it is that has to be done. Although these two components are interconnected, they are functionally distinct (Cohen, Dixon, Lindsay, & Masson, 2003).