action slips

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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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.


  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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