procedural memory

More about motor memory

I don’t often talk about motor or skill memory — that is, the memory we use when we type or drive a car or play the piano. It’s one of the more mysterious domains of memory. We all know, of course, that this is a particularly durable kind of memory. It’s like riding a bicycle, we say — meaning that it’s something we’re not likely to have forgotten, something that will come back to us very readily, even if it’s been a very long time since we last used the skill.

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Forgetting a skill or procedure

  • Memory for skills — procedural memory — is stored as action sequences, in our unconscious memory.
  • Because this type of memory is very reliable, failures are usually particularly puzzling and even distressing.
  • Because the memory is less accessible, we also tend to have problems dealing with failures.
  • Failures occur when an action sequence becomes disrupted for some reason. When this happens, we have to retrieve the knowledge stored in our conscious memory, that we used when learning the skill.

Have you ever been driving a car and suddenly you’re not sure what to do? You’re traveling along in usual automatic fashion and there comes a moment when you need to engage a new subroutine — say, you need to give way at an intersection, or you stall at the traffic lights, or you stop the car — and suddenly, you don’t know what to do. There’s a flash of panic, even while you’re thinking, “This is stupid, I’ve done this a thousand times”, and then, maybe it’s all right, maybe you have to take a moment to get your head in the right space, and ... okay, you’re off again, control safely in the hands of the automatic pilot.

But you’re unsettled. There are lots of ways our memory fails us. Some of these are very common, so common we just accept them — noone (well, few of us) expect our memories to be 100% perfect all the time. But procedural memory — the memory that allows us to drive a car, ride a bike, type, play the piano, etc — is different from other types of memory. We don’t say “it’s like riding a bicycle” without reason. Once we’ve truly mastered a skill, we expect to have that, for ever. And, for the most part, we do.

The thing about procedural memory — the big difference between it and so-called declarative memory — is that it is not in conscious memory. That’s its huge advantage; we could never perform skills fast enough if they were under conscious control. As we acquire a skill, the declarative information we learn (‘use your little finger on the “a”; the “s” is next to the “a”; the “d” is next to the “s” ’ etc) is transformed into so-called “procedural rules”, which are completely internalized, beyond our conscious manipulation. This greatly reduces the involvement of working memory, and protects the skill from the types of interference that other types of memory are vulnerable to.

It also means that when we do have a failure, we really don’t know how to deal with it. A conscious mental search is not going to retrieve the needed information, because the information we want is not in our accessible database. So what usually happens is that we are forced to default to our backup — the declarative information we encoded during the original learning process. It is this that accounts for the lack of fluency in the subsequent actions; to regain fluency, you must engage the unconscious action sequence.

I don’t know of any research that has looked into these occasional glitches, but I presume that what happens is that the action sequence doesn’t immediately engage. As soon as it doesn’t, we pay attention — that makes it even more likely that the action sequence won’t be triggered, because conscious awareness is precisely what we don’t want.

One piece of research that is relevant to this is a recent study that looked at the phenomenon of “choking” — top athletes performing below par at crucial moments. It’s suggested that the problem lies in part in the athlete paying too much attention to what they’re doing. Skills are the one area of memory where too much attention is deleterious to performance!

I think the best way to deal with this very occasional glitch in performance is to relax, stop thinking about what you’re doing, go back a little in the action sequence to an obvious starting point (if you can’t or don’t need to physically re-do earlier steps, mimic the steps). Remember that skills are stored as sequences, and it’s hard to break in halfway through a sequence, you need to start at the beginning.

You can read more about skill memory and about the best way to practice.

You might also be interested in a related (but separate) issue, that of action slips, which are a product of a lack of attention, not a surfeit.

This article originally appeared in the November 2004 newsletter.

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Multitasking

  • Doing more than one task at a time requires us to switch our attention rapidly between the tasks.
  • This is easier if the tasks don't need much attention.
  • Although we think we're saving time, time is lost when switching between tasks; these time costs increase for complex or unfamiliar tasks.
  • Both alcohol and aging affect our ability to switch attention rapidly.

A very common situation today, which is probably responsible for a great deal of modern anxiety about failing memory, is that where we're required to “multitask”, that trendy modern word for trying to do more than one thing at a time. It is a situation for which both the normal consequences of aging and low working memory capacity has serious implications.

There’s an old insult along the lines of “he can’t walk and chew gum”. The insult is a tacit acknowledgment that doing two things at the same time can put a strain on mental resources, and also recognizes (this is the insult part!) that well-practiced activities do not place as much demand on our cognitive resources. We can, indeed, do more than one task at a time, as long as only one of the tasks requires our attention. It is attention that can’t be split.

You may feel that you can, in fact, do two tasks requiring attention simultaneously. For example, talking on a cellphone and driving!

Not true.

What you are in fact doing, is switching your attention rapidly between the two tasks, and you are doing it at some cost.

How big a cost depends on a number of factors. If you are driving a familiar route, with no unexpected events (such as the car in front of you braking hard, or a dog running out on the road), you may not notice the deterioration in your performance. It also helps if the conversation you are having is routine, with little emotional engagement. But if the conversation is stressful, or provokes strong emotion, or requires you to think … well, any of these factors will impact on your ability to drive.

The ability to switch attention between tasks is regulated by a function called prefrontal cortex. This region of the brain appears to be particularly affected by aging, and also by alcohol. Thus, talking on a cellphone while driving drunk is a recipe for disaster! Nor do you have to actually be under the influence to be affected in this way by alcohol; impaired executive control is characteristic of alcoholics.

More commonly, we get older, and as we get older we become less able to switch attention fast.

The ability to switch attention is also related to working memory capacity.

But multitasking is not only a problem for older adults, or those with a low working memory capacity. A study [1] using young adults found that for all types of tasks, time was lost when switching between tasks, and time costs increased with the complexity of the tasks, so it took significantly longer to switch between more complex tasks. Time costs also were greater when subjects switched to tasks that were relatively unfamiliar.

Part of the problem in switching attention is that we have to change “rules”. Rule activation takes significant amounts of time, several tenths of a second — which may not sound much, but can mean the difference between life and death in some situations (such as driving a car), and which even in less dramatic circumstances, adds appreciably to the time it takes to do tasks, if you are switching back and forth repeatedly.

To take an example close to home, people required to write a report while repeatedly checking their email took half again as long to finish the report compared to those who didn't switch between tasks!

In other words, while multitasking may seem more efficient, it may not actually BE more efficient. It may in fact take more time in the end, and the tasks may of course be performed more poorly. And then there is the stress; switching between tasks places demands on your mental resources, and that is stressful. (And not only are we poorer at such task-switching as we age, we also tend to be less able to handle stress).

There is another aspect to multitasking that deserves mention. It has been speculated that rapid switching between tasks may impede long-term memory encoding. I don’t know of any research on this, but it is certainly plausible.

So, what can we do about it?

Well, the main thing is to be aware of the problems. Accept that multitasking is not a particularly desirably situation; that it costs you time and quality of performance; that your ability to multitask will be impeded by fatigue, alcohol, stress, emotion, distraction (e.g., don’t add to your problems by having music on as well); that your ability will also be impaired by age. Understand that multitasking involves switching attention between tasks, not simultaneous performance; and that it will therefore be successful to the extent that the tasks are familiar and well-practised.

This article originally appeared in the February 2005 newsletter.

References: 

Rubinstein, J.S., Meyer, D.E. & Evans, J.E. 2001. Executive Control of Cognitive Processes in Task Switching. Journal of Experimental Psychology - Human Perception and Performance, 27 (4), 763-797.

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Action Slips

There is a very common form of forgetfulness that is not really a failure of memory. When we get in our car to drive to place A and find ourselves instead on the road to the more familiar place B, this is not a failure of memory. When we clear the table and find ourselves putting the margarine in the dishwasher or the dirty plate in the fridge, this is not a failure of memory. When we go into a room intending to do one thing and do something else instead, this is not, really, a failure of memory.

These are absentminded errors, and they happen to all of us. They have also been termed action slips, and this term is useful because it points more precisely to the nature of these errors. Let's look at the characteristics of action slips:

  • they usually occur during the performance of tasks that are so highly practised they are largely automatic
  • they usually occur when we are preoccupied or distracted
  • many involve intrusions of other habitual actions that share some characteristics with the intended action
  • such habit intrusions are more likely to occur when:
    • we're departing in some way from our usual routine (for example, you decide to stop adding milk and sugar to your coffee, then finding yourself doing it automatically)
    • the situation has changed, demanding a change in our usual routine (for example, a much-visited shop moves premises, but you keep going to its old location)
    • the situation shares features with a highly familiar situation (for example, you try and open a friend's car with your own car key)

Other types of action slips are:

  • place-losing errors - where you've lost your "place" in an action sequence, and so omit or repeat part of the sequence (for example, because of wheat sensitivities in my family, I make our own bread; accordingly, it is a highly practiced recipe, and I add all the ingredients in a fixed order. If something happens to distract me in the course of it, I may be unsure where I am in the sequence, and risk omitting or repeating an ingredient)
  • blends - where you get confused between two active tasks (for example, you write an email while thinking about the next email you're going to write, and address the current email to the correspondent for the second email)
  • reversals - where you get confused between parts of the same task (for example, you put an empty ice cube tray in the freezer, then turn to the tap to fill it)

You can see from all this that these everyday errors occur in the context of action sequences - that is, sequences of actions that we have practised so often they have become automatic. Dressing, undressing, washing, making coffee or tea, even making quite complicated recipes - these are all common examples of action sequences.

You can see why action slip is therefore a good name for these types of error.

Is there anything we can do to minimize action slips? Well, the standard advice is to pay attention to what you're doing, but of course the whole point of action sequences is that they free our mind from needing to pay attention, so this is not a strategy I particularly recommend. However, if there are some action slips that you are particularly prone to, you might want to try this.

The most useful thing you can do is simply be aware of the circumstances that set you up for such errors. Then you can either:

  • make a sterling effort to pay attention when it's important to you (for example, both my partner and I are careful when we are driving and need to depart from familiar routes, to remind ourselves - or each other - of our destination at key points), or
  • use an object to signal that you have done something, or remind you where you are in a sequence (to take the recipe example again, you could move used ingredients to a particular part of the kitchen bench), or
  • decide it's not important!

This article originally appeared in the December 2003 newsletter.

References: 

  1. Harris, J.E. & Morris, P.E. (eds.) 1984. Everyday memory, actions and absent-mindedness. Academic Press.
  2. Reason, J.T. & Mysielska, K. 1982. Absent-minded? The psychology of mental lapses and everyday errors. Englewood Cliffs, NJ.: Prentice-Hall.

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Learning a new skill

To master a skill:

  • Practice it until you reach the stage where actions follow automatically
  • Practice more efficiently, by:
    • varying your actions
    • providing immediate feedback
    • spacing out your practice

Remembering a skill is entirely different from remembering other kinds of knowledge. It’s the difference between knowing how and knowing that.

Practice, practice, practice

Practice is the key to mastering a skill. One of the critical aspects is assuredly the fact that, with practice, the demands on your attention get smaller and smaller. Interestingly (and probably against common sense), there appears to be no mental limit to the improvement you gain from practice. Your physical condition limits how much improvement you can make to a practical skill (although, in practice, few people probably ever approach these limits), but a cognitive skill will continue to improve as long as you keep practicing. One long-ago researcher had two people perform 10,000 mental addition problems, and they kept on increasing their speed to the end.

How to get the most out of your practice

While practice is the key, there are some actions we can take to ensure we get the most value out of our practice:

  • Learn from specific examples rather than abstract rules
  • Provide feedback while the action is active in memory (i.e., immediately). Try again while the feedback is active in memory.
  • Practice a skill with subtle variations (such as varying the force of your pitch, or the distance you are throwing) rather than trying to repeat your action exactly.
  • Space your practice (maths textbooks, for example, tend to put similar exercises together, but in fact they would be better spaced out).
  • Allow for interference with similar skills: if a new skill contains steps that are antagonistic to steps contained in an already mastered skill, that new skill will be much harder to learn (e.g., when I changed keyboards, the buttons for page up, page down, insert, etc, had been put in a different order — the conflict between the old habit and the new pattern made learning the new pattern harder than it would have been if I had never had a keyboard before). The existing skill may also be badly affected.
  • If a skill can be broken down into independent sub-skills, break it down into its components and learn them separately, but if components are dependent, learn the skill as a whole (e.g., computer programming can be broken into independent sub-skills, but learning to play the piano is best learned as a whole).

References: 

  1. Anderson, J.R., Fincham, J.M. & Douglass, S. 1997. The role of examples and rules in the acquisition of a cognitive skill. Journal of Experimental Psychology: Learning, Memory and Cognition, 23, 932-945.
  2. Chase, W.G. & Ericsson, K.A. 1981. Skilled memory. In J.R. Anderson (ed.) Cognitive skills and their acquisition. Hillsdale, NJ: Erlbaum.
  3. Wulf, G. & Schmidt, R.A. 1997. Variability of practice and implicit motor learning. Journal of Experimental Psychology: Learning, Memory and Cognition, 23, 987-1006.

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