Figure 510

Response times on a decision task as a function of memory-set size, display-set size, and consistent vs. varied mapping. Data from Shiffrin and Schneider (1977).

• They are unavailable to consciousness.

• They are unavoidable (i.e., they always occur when an appropriate stimulus is presented, even if that stimulus is outside the field of attention).

As Hampson (1989, p. 264) pointed out, "Criteria for automatic processes are easy to find, but hard to satisfy empirically" For example, the requirement that automatic processes should not need attention means that they should have no influence on the concurrent performance of an attention-demanding task. This is rarely the case (see Pashler, 1998). There are also problems with the unavoidability criterion. The Stroop effect, in which the naming of the colours in which words are printed is slowed down by using colour words (e.g., the word YELLOW printed in red), has often been regarded as involving unavoidable and automatic processing of the colour words. However, Kahneman and Henik (1979) found that the Stroop effect was much larger when the distracting information (i.e., the colour name) was in the same location as the to-be-named colour rather than in an adjacent location. Thus, the processes producing the Stroop effect are not entirely unavoidable, and so are not completely automatic.

Few processes are fully automatic in the sense of conforming to all the criteria, with a much larger number of processes being only partially automatic. Later in this section we consider a theoretical approach (that of Norman & Shallice, 1986) which distinguishes between fully automatic and partially automatic processes.

Shiffrin and Schneider's theory

Shiffrin and Schneider (1977) and Schneider and Shiffrin (1977) argued for a theoretical distinction between controlled and automatic processes. According to them:

• Controlled processes are of limited capacity, require attention, and can be used flexibly in changing circumstances.

• Automatic processes suffer no capacity limitations, do not require attention, and are very hard to modify once they have been learned.

Schneider and Shiffrin made use of a task in which participants memorised one, two, three, or four letters (the memory set), were then shown a visual display containing one, two, three, or four letters, and finally decided as rapidly as possible whether any one of the items in the visual display was the same as any one of the items in the memory set. The crucial manipulation was the type of mapping used. With consistent mapping, only consonants were used as members of the memory set, and only numbers were used as distractors in the visual display (or vice versa). Thus, if a participant were given only consonants to memorise, then he or she would know that any consonant detected in the visual display must be an item from the memory set. With varied mapping, a mixture of numbers and consonants was used to form the memory set and to provide distractors in the visual display.

There were striking effects of the mapping manipulation (see Figure 5.10). The numbers of items in the memory set and visual display greatly affected decision speed in the varied mapping conditions, but not in the consistent mapping conditions. According to Schneider and Shiffrin (1977), a controlled search process was used with varied mapping. This involves serial comparisons between each item in the memory set and each item in the visual display until a match is achieved or every comparison has been made. In contrast, performance with consistent mapping reflects the use of automatic processes operating independently and in parallel. According to Schneider and Shiffrin (1977), these automatic processes evolve as a result of years of practice in distinguishing between letters and numbers.

The notion that automatic processes develop through practice was tested by Shiffrin and Schneider (1977). They used consistent mapping with the consonants B to L forming one set and the consonants Q to Z forming the other set. As before, items from only one set were always used in the construction of the memory set, and the distractors in the visual display were all selected from the other set. There was a great improvement in performance over 2100 trials, which seemed to reflect the growth of automatic processes.

The greatest problem with automatic processes is their lack of flexibility, which is likely to disrupt performance when the prevailing circumstances change. This was confirmed in the second part of the study. The initial 2100 trials with one consistent mapping were followed by a further 2100 trials with the reverse consistent mapping. This reversal of the mapping conditions greatly disrupted performance. Indeed, it took nearly 1000 trials under the new conditions before performance recovered to its level at the very start of the experiment!

Shiffrin and Schneider (1977) carried out further experiments in which participants initially tried to locate target letters anywhere in a visual display, but were then instructed to detect targets in one part of the display and to ignore targets elsewhere. Participants were less able to ignore part of the visual display when they had developed automatic processes than when they had made use of controlled search processes. As Eysenck (1982, p. 22) pointed out, "Automatic processes function rapidly and in parallel but suffer from inflexibility; controlled processes are flexible and versatile but operate relatively slowly and in a serial fashion."

Evaluation

Shiffrin and Schneider's (1977) theoretical approach is important, but is open to criticism. There is a puzzling discrepancy between theory and data with respect to the identification of automaticity. The theoretical assumption that automatic processes operate in parallel and place no demands on capacity means there should be a slope of zero (i.e., a horizontal line) in the function relating decision speed to the number of items in the memory set and/or in the visual display when automatic processes are used. In fact, decision speed was slower when the memory set and the visual display both contained several items (see Figure 5.10).

Shiffrin and Schneider's approach is descriptive rather than explanatory. The claim that some processes become automatic with practice is uninformative about what is actually happening. Practice may simply lead to a speeding up of the processes involved, or it may lead to a dramatic change in the nature of the processes themselves. Cheng (1985) used the term "restructuring" to refer to the latter state of affairs. For example, if you are asked to add ten twos, you could do this by adding two and two, and then two to four, and so on. Alternatively, you could short-circuit the process by simplying multiplying ten by two. Thus, simply finding that practice leads to automaticity does not indicate whether the same processes are being performed more efficiently or whether entirely new processes are being used.

Cheng (1985) argued that most of Shiffrin and Schneider's findings on automaticity were actually based on restructuring. She claimed that participants in the consistent mapping conditions did not really search systematically for a match. If, for example, they knew that any consonant in the visual display had to be an item from the memory set, then they could simply scan the visual display looking for a consonant without any regard to which consonants were actually in the memory set. Schneider and Shiffrin (1985) pointed out that some findings could not be explained in terms of restructuring. For example, the finding that participants could not ignore part of the visual display after automatic processes had been acquired does not lend itself to a restructuring explanation.

Norman and Shallice's theory

Norman and Shallice (1986) distinguised between fully automatic and partially automatic processes. They identified three levels of functioning:

• Fully automatic processing, controlled by schemas (organised plans).

• Partially automatic processing, involving contention scheduling without deliberate direction or conscious control; contention scheduling is used to resolve conflicts among schemas.

• Deliberate control by a supervisory attentional system; Baddeley (1986) argued that this system resembled the central executive of the working memory system (see Chapter 6).

According to Norman and Shallice (1986), fully automatic processes occur with very little conscious awareness of the processes involved. Such automatic processes would often disrupt behaviour if left entirely to their own devices. As a result, there is an automatic conflict resolution process known as contention scheduling. This selects one of the available schemas on the basis of environmental information and current priorities. There is generally more conscious awareness of the partially automatic processes involving contention scheduling than of fully automatic processes. Finally, there is a higher-level supervisory attentional system. This system is involved in decision making and trouble-shooting, and it permits flexible responding in novel situations. The supervisory attentional system may well be located in the frontal lobes (see Chapter 6).

Section .summary

The theoretical approach of Norman and Shallice (1986) includes the interesting notion that there are two separate control systems: contention scheduling and the supervisory attentional system. This contrasts with the views of many previous theorists that there is a single control system. The approach of Norman and Shallice is preferable, because it provides a more natural explanation for the fact that some processes are fully automatic, whereas others are only partially automatic.

Instance theory

Logan (1988) pointed out that most theories do not indicate clearly how automaticity develops through prolonged practice. He tried to fill this gap by putting forward instance theory based on these assumptions:

• Separate memory traces are stored away each time a stimulus is encountered and processed.

• Practice with the same stimulus leads to the storage of increased information about the stimulus, and about what to do with it.

• This increase in the knowledge base with practice permits rapid retrieval of relevant information when the appropriate stimulus is presented.

• "Automaticity is memory retrieval: performance is automatic when it is based on a single-step direct-access retrieval of past solutions from memory" (Logan, 1988, p. 493).

• In the absence of practice, responding to a stimulus requires thought and the application of rules. After prolonged practice, the correct response is stored in memory and can be accessed very rapidly.

These theoretical views make coherent sense of many characteristics of automaticity. Automatic processes are fast because they require only the retrieval of "past solutions" from long-term memory. Automatic processes have little effect on the processing capacity available to perform other tasks, because the retrieval of heavily over-learned information is relatively effortless. Finally, there is no conscious awareness of automatic processes, because no significant processes intervene between the presentation of a stimulus and the retrieval of the appropriate response.

Logan (1988, p. 519) summarised instance theory as follows: "Novice performance is limited by a lack of knowledge rather than by a lack of resources...Only the knowledge base changes with practice." Logan is probably right in his basic assumption that an understanding of automatic, expert performance will require detailed consideration of the knowledge acquired with practice, rather than simply processing changes.

Logan, Taylor, and Etherton (1996) studied automaticity. Two words were presented together on each trial, one of which was red or green and the other of which was white. Specific words (e.g., chair) were always presented in the same colour. One group of participants had to make one of three decisions with respect to the coloured word:

1. It does not belong to the target category (e.g., countries).

2. It belongs to the target category and is coloured red.

3. It belongs to the target category and is coloured green.

There were 512 trials of training, and the speeding up of performance over these trials suggested that automatic processes had developed. There were then 32 transfer trials, on which the colour of each word was reversed from the training trials. The key finding was that colour reversal disrupted performance, indicating that colour information influenced automatic performance during transfer.

Another group of participants was treated exactly the same during training. However, their task on the transfer trials did not require them to attend explicitly to the colour of the words. They had to make one of two decisions with respect to the coloured word:

1. It does not belong to the target category.

2. It belongs to the target category.

Would we expect colour reversal to disrupt performance for these participants? Information about colour had been thoroughly learned during training, and so might produce disruption via automatic processes. In fact, there was no disruption. Thus, knowledge stored in memory as a result of prolonged practice may or may not be produced automatically depending on the precise conditions of retrieval.

How did Logan et al. (1996) explain these findings? Their starting point was the notion that automaticity is a memory phenomenon. The relationship between encoding and retrieval is important for an explanation of memory performance (see Chapter 6). According to Logan et al. (1996, p. 621):

Automatic performance depends on both encoding and retrieval, so evidence that some aspect of a stimulus is important in automatic performance suggests that that aspect was encoded in the instance.

However, evidence that some aspect of a stimulus is not important in automatic performance does not mean that that aspect was not encoded. It may be available to some other retrieval task.

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