Slips of Action

Absentmindedness and Slips of Action

Errors of prospective memory Opens in new window involve failing to carry out a plan or to comply with an instruction to do something. These can be distinguished from absentmindedness and slips of action. As defined by Norman (1981):

Slips of action are a common experience in daily life and occur both in speech and in nonverbal behavior. In this entry, we will be concerned with errors in nonverbal actions.

We all find ourselves, from time to time, doing things like pouring coffee into the sugar bowl, throwing cheques into the waste-paper basket, or driving towards one destination when we actually intended to go to quite a different one. By analyzing the nature and incidence of these kinds of slips, researchers have been able to infer some of the characteristics of the mechanisms that control the performance of action sequences.

Classifying Slips of Action

Reason (1979) asked 35 volunteers to keep a diary record of their slips of action. In two weeks the diaries yielded 400 of these slips, and Reason was able to identify several different categories of error.

1. Repetition errors

Forgetting Opens in new window that an action has already been performed and repeating it, e.g.

Reason called slips of action of this nature storage failures and 40% of his corpus consisted of repetition errors of this kind.

2. Goal switches

Forgetting the goal of a sequence of actions and switching to a different goal, e.g.

These slips (which Reason called test failures) formed 20% of his corpus.

3. Omissions and reversals

Omitting or wrongly ordering the component actions of a sequence, e.g.

In Reason’s study 18% of the errors were of this kind.

4. Confusions/blends

Confusing objects involved in one action sequence with those involved in another sequence, e.g.

Or confusing the actions from one sequence with actions from another sequence, as in the case of a woman who reported throwing her earrings to the dog and trying to clip dog biscuits on to her ears.

In these cases, there has been crosstalk between two programs and different action sequences have been confused with each other. About 16% of errors in Reason’s study were confusions.

Although the diary records produced good descriptive evidence for the occurrence of these different types of error, the reported incidence of each kind may not be a very accurate record of actual incidence.

A particular kind of slip may be reported as more frequent because it is more disruptive and therefore more noticeable.

Slips that involve confusions are likely to be particularly memorable because they tend to produce rather ludicrous results, but other slips of action may go unnoticed.

Automatic and Attentional Processes

Some characteristic features have been identified from the classification of slips. The most important finding is that slips of action occur predominantly with highly practiced, overlearned, routine activities. Making cups of tea and coffee, for example, are activities that give rise to many of the reported slips of action.

This is partly because actions that occur very frequently provide more opportunities for slips to occur. However, the predominance of errors in making tea and coffee is not just evidence of a national obsession, but also arises because these are routine, repeated actions.

To understand the underlying mechanism, researchers have applied the distinction between automatic and attentional processes formulated by Shiffrin and Schneider (1977).

Highly practiced actions become automatic and can then be carried out according to pre-set instructions, with little or no conscious monitoring. Reason and Mycielska (1982) called this mode of action control an open loop system. Automatic, or open loop, processes differ from attentional, or closed loop, processes.

A good example of this distinction between automatic and attentional processes occurs when you are driving a car. Emerging from a road junction is (or ought to be) an attentionaal process. The traffic must be scanned, distances and speeds assessed, and the driver is consciously thinking about the actions that need to be implemented.

In contrast, for the practiced driver, changing gears is an automatic process. The actions involved do not need to be consciously monitored, and can usually be carried out successfully while the driver is attending to something quite different, like chatting to a passenger or calculating petrol consumption.

Automatic action sequences have the advantage that they can be carried out while the conscious mind is free to engage in other parallel activities.

However, automatization can lead to slips of action. Even automatic actions may need intermittent attention to keep them on the right track, and slips of action occur if attention is not shifted to the ongoing action at a critical point in the sequence.

Predisposing Conditions

An action sequence (or program) that is in frequent use is “stronger” than one that is used less often.

There is a tendency for a stronger program to take over from a weaker program, particularly if some component stages are common to both, and this type of slip is sometimes known as a “strong habit intrusion” or a “capture error”.

Slips of action often occur at junctions where two programs share a particular component and there is an involuntary switchover to the stronger program.

The stronger “going to bed” program took over from the “changing clothes” program because both shared the common components of entering the bedroom and removing the jacket. The types of slip classed as Goal Switches and Confusions may both occur because of strong habit intrusions.

Another predisposing condition, besides automaticity and competition from stronger habits, has been identified by Reason (1984).

In addition to these predisposing circumstances, there are predisposing internal states. Some individuals are much more prone to make these kinds of errors than other people, but many people find that slips of action increase with tiredness, illness, or stress.

Broadbent et al. (1982) developed the Cognitive Failures Questionnaire (CFQ) Opens in new window to serve as an index of an individual’s susceptibility to slips of action, as well as other failures of memory and perception.

Respondents were asked to assess the frequency with which they experienced specific examples of cognitive failure.

Broadbent et al. established that CFQ scores were not related to performance on tests of immediate and delayed memory, or to perception as measured by performance on a word identification task.

Martin and Jones (1984) later attempted to establish whether CFQ scores were related to any other aspects of cognitive ability, or to personality traits and internal states.

CFQ scores were also related to forward digit span, which tests ability to maintain a set of items in the correct serial order.

This ability is also involved in carrying out action sequences, and the kind of slips classified as omissions and reversals arise as a result of breakdown in the maintenance of the correct serial order for components in an action sequence.

Besides these measures of cognitive ability, Martin and Jones reported an association between frequent cognitive failures and high anxiety, and cited studies by Parkes (1980) comparing nurses working on high-stress wards and low-stress wards, which suggested that cognitive failures are related to vulnerability to the effects of stress.

Just as the level of representation may be an important factor in failures of prospective memory, it can also underlie slips of action.

Norman (1988) suggested that some slips are “description errors” and are caused because the action has been ambiguously represented in memory.

In one of his examples, someone who threw a dirty shirt into the toilet instead of into the laundry basket had apparently represented the action too generally as “throw object into an open container”.