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prospective memory

Forgetting to do things

  • Forgetting future tasks and events is the most common type of memory failure
  • Older adults are in general no worse at this type of remembering than younger adults
  • Older adults may have more difficulty at remembering to do actions at particular times
  • Older adults also need to make more effort in situations when an action cannot be performed immediately, but must be held in memory for a brief period.

The other day I was sitting in the sunshine in my living room going through some journal articles I'd photocopied. I realized I needed to staple the pages together and went down to my study to get the stapler. Approaching my desk, I decided to check my email while I was there. And then, I decided to check my library account online to see whether a book I had requested had turned up. When I'd done that, I went back upstairs to my papers. Where I realized, of course, that I'd forgotten the stapler.

This type of memory failure — going to do something, getting sidetracked, doing something else and forgetting the original task — is familiar to all of us. As are everyday memory failures like forgetting to put the garbage out; forgetting to take medication at the right time; forgetting a dentist appointment (although there's more than one reason for that!).

This type of memory failure — forgetting the future, as it were — is a failure of a type of memory called prospective memory, and it is probably the most common type of memory failure older adults suffer from. And probably the biggest concern.

It's a concern because it's a failure of memory that has consequences, and those consequences are often not only obvious to ourselves, but also to others. Which makes us feel worse, of course.

But it's not just a matter of being embarrassed. Older adults are particularly vulnerable to thoughts that they are "losing" their memory — and the fear of Alzheimer's lurks in all of us.

So, should you be worried if you forget what you're doing?

Like other types of forgetting or absent-mindedness, it depends on the degree of your forgetfulness. But prospective memory failure is common among older adults for a very good reason. Not because it's a precursor of cognitive impairment, but because it's the most common type of memory failure for everyone.

In fact, older adults in general are no worse than anyone else in this particular memory domain, although they may worry about it more (because they worry about any memory failure more).

In some aspects of prospective memory, older adults are actually better than younger adults! One reason for this is that they are more likely to use memory aids — like writing down reminders, or putting reminder objects in strategic places — to help them remember.

However, it does seem that older adults may do less well at remembering things that have to be done at particular times, and one reason for this seems to be that they tend to be poorer at monitoring time. In these cases, it's therefore a good idea to use timers as reminders.

Older adults also seem to have more trouble in the situation when a remembered intention cannot be performed immediately, but must be held in memory for a brief period. Even 5-10 seconds is too long! Tasks that you are "just about" to perform, but in fact are not doing that very second (because you have some other intervening task to do first) are probably particularly dangerous because you don't feel a need to make an effort to remember them (because you are "just about" to do it). But without rehearsal, information falls out of working memory (the stuff we're holding in the conscious "forefront" of our mind) in seconds. So you do need to make an effort. And often, that's all it needs.

You can read more about planning memory strategies in my book on planning memory.

 

Planning to Remember

External memory aids

What are external memory aids?

External memory aids include such strategies as:

  • taking notes
  • making shopping lists
  • entering appointments in a diary or on a calendar
  • writing a memo to yourself
  • writing on the back of your hand
  • taking photographs
  • using clocks, oven timers, alarms on watches, etc
  • putting objects in a conspicuous place
  • putting a knot in your handkerchief
  • asking someone to help you remember

Making lists

Making lists or writing reminder notes to yourself, is one of the most widespread external memory aids. It seems that list-making is primarily helpful as a way of organizing (encoding) information, rather than its more obvious role in retrieving. More often than not, people do not actually use the list or note to ‘remember’. The act of making it is sufficient to aid later recall.

However, there are situations where list-making appears appropriate but is not in fact the best strategy. For example, one study found that waitresses who went from table to table to take drink orders were much better at remembering the orders if they visualized the drinks in particular locations rather than when they wrote the orders down1. It is perhaps the time pressure in that kind of situation that makes an internal strategy more effective than an external one.

When to use mental strategies

  • when you can’t rely on external prompts (e.g., acting in a play)
  • when external prompts are difficult to prepare (e.g., because you lack writing materials) or hard to use (you have OOS in your writing hand)
  • when you didn’t expect to need to recall something, and have nothing prepared
  • when using external aids interferes with other behavior (understanding what’s going on; taking orders; etc)
  • when carrying external aids would be undesirable or inconvenient (e.g., when driving)
  • when the interval between learning and recall is very short (as when you need to remember a phone number only long enough to dial it)

When to use external memory aids

  • when a number of interfering activities occur between encoding and recall (e.g., having to remember to buy groceries after work)
  • when there is a long time between encoding and recall (e.g., needing to make a doctor’s appointment two months in the future)
  • when internal aids are not trusted to be sufficiently reliable (as when precise details need to be remembered; or strict timing — when to check a cake in the oven)
  • when information is difficult, and doesn’t cohere easily (e.g., remembering lectures)
  • when there is insufficient time to properly encode information
  • when memory load is to be avoided (as when you are attending to more than one activity)

How effective are external memory aids?

In general, external aids are regarded as easier to use, more accurate, and more dependable, than mental strategies. However, with the exception of note-taking, there has been little research into the effectiveness of external memory aids. The most that can be said is that, by and large, people believe they can be effective (with the emphasis, perhaps, on ‘can’).

One problem with external aids is that most of them are highly specific in their use. Their effective use also requires good habits. It’s no good remembering to make a note in your diary if you don’t remember to look in it.

The Memory Key

References
  • Intons-Peterson, M.J. & Fourrier, J. 1986. External and internal memory aids: when and how often do we use them? Journal of Experimental Psychology: General, 115, 267-280.
  • Intons-Peterson, M.J. & Newsome, G.L. III. 1992. External memory aids: effects and effectiveness. In D. Herrmann, H. Weingartner, A. Searleman & C. McEvoy (eds.) Memory Improvement: Implications for Memory Theory. New York: Springer-Verlag.
  1. Bennett, H.L. 1983. Remembering drinks orders: The memory skills of cocktail waitresses. Human Learning, 2, 157-169.

Remembering to do things

  • Remembering intentions is more difficult than remembering past events
  • It's the lack of cues to remembering that make remembering intentions so difficult
  • That's why using physical objects to cue our remembering is so common
  • To remember intentions without relying on physical reminders, it's best to concentrate on working out an event or time that will trigger your remembering. Set your mind to remember the link between the trigger and the intention, not the intention on its own.

Planning memory contains your plans and goals (such as, “I must pick up the dry-cleaning today”; “I intend to finish this project within three months”). Forgetting an appointment or a promise is one of the memory problems people get most upset about.

Why remembering to do things is so difficult

Remembering intentions is in fact much more difficult than remembering events that have happened, and the primary reason is the lack of retrieval cues. This is why, of all memory tasks, remembering to do things relies most heavily on external memory aids. Reminder notes, calendars, diaries, watch-alarms, oven-timers, leaving objects in conspicuous places — all these external aids are acting as cues to memory.

In partial compensation for the paucity of effective retrieval cues , planning memories are more easily triggered by quite marginal cues. Thus a friend of mine was reminded that her son’s friend would be spending Saturday night with them when she saw an advertisement for a movie about John F. Kennedy (the child’s father had the same initials: JFK).

Setting up effective cues

When we form an intention, we usually link it either to an event (“after we go to the swimming-pool, we’ll go to the supermarket”) or a time (“at 2pm I must ring Fred”). But these trigger events or times frequently fail to remind us of our intention.

This is often because the trigger is not in itself particularly distinctive. Your failure to remember to ring Fred at 2pm, for example, may be because you paid little attention to the clock reaching that time, or because there were other competing activities triggered by that same time signal.

Moreover, not all planning is linked to a trigger event or time. Quite a lot of planning simply waits upon an appropriate opportunity (“must buy some stamps sometime”). Such intentions usually need quite explicit cues. Thus, if I happened to see stamps on sale, I would probably remember my intention, but walking past, or even into, a shop that happens to sell stamps, may not be enough to trigger my memory.

On the other hand, I might keep being reminded of my intention when I am in the same context as when I originally formed the intention (when I am not in a position to carry it out!) — hence your increasing exasperation that you can never remember a particular intention when you can do anything about it.

Link the trigger and the intention

To deal with opportunistic planning, you should try to specify features of an appropriate opportunity. Thus, to remember to buy bread on the way home, you should think about what actions you need to take to buy the bread (for example, going a different route) and try to form a strong link between the trigger event and your action (“today when I get to the traffic lights I’ll turn left”).

A reminder of your intention is much less effective than being reminded of both the trigger event and the intended activity. Even being reminded of the trigger event is better than being reminded of the intention on its own.

To remind yourself to do something, focus on the trigger not the intent itself.

Don’t assume that because something is important to you, you will automatically remember it — somewhat to their surprise, researchers have found no evidence that personal importance has any effect on the likelihood of remembering to do something.

You can read more about planning memory strategies in my book on planning memory.

 

Planning to Remember

References
  • Guynn, M.J., McDaniel, M.A. & Einstein, G.O. 1998. Prospective memory: When reminders fail. Memory & Cognition, 26, 287-298.
  • Morris, P.E. 1992. Prospective memory: remembering to do things. In M.M. Gruneberg, & P. Morris (eds.) Aspects of memory. Vol.1: The practical aspects. 2nd ed. London: Routledge.