Cognitive Psychology: Connecting Mind, Research and Everyday Experience, 3rd Edition

Something to Consider • 141

The participants’ task was to respond to the test display by indicating

whether the orientations of the red rectangles in the cued side of the test dis-

play was the same as or different from the orientations of the red rectangles

on the cued side of the memory display. In the examples in Figure 5.27, the

answers would be “same.”

The results in ● Figure 5.28 show the size of the ERP responses for both

groups. The left pair of bars in Figure 5.28 show that the ERP response when

just red rectangles were presented was similar for the high-capacity and low-

capacity participants. However, the right pair of bars indicate that adding

blue rectangles had little effect on the response of the high-capacity group,

but caused an increase in the response of the low-capacity group.

The fact that adding the two blue rectangles had little effect on the

response of the high-capacity group means that these participants were very

effi cient at ignoring the distractors, so the irrelevant blue stimuli did not take

up any space in working memory. Because allocating attention is a function

of the central executive, this means that the central executive was functioning

well for these participants.

The fact that adding the two blue rectangles caused a large increase in the

response of the low-capacity group means that these participants were not able

to ignore the irrelevant blue stimuli, and the blue rectangles were therefore tak-

ing up space in working memory. The central executive of these participants is

not operating as effi ciently as the central executives of the high-capacity par-

ticipants. Vogel and coworkers concluded from these results that some people’s

central executives are better at allocating attention than others’. The reason

this is important is that other experiments have shown that people with more

effi cient working memories are more likely to perform well on tests of reading

and reasoning ability and on tests designed to measure intelligence.

Something to Consider

The Advantages of Having

a More Efficient Working Memory

At the beginning of a chapter on individual differences in working memory, Andrew

Conway and coworkers (2007, p. 3) state:

The ability to mentally maintain information in an active and readily accessible state,

while concurrently and selectively processing new information, is one of the greatest

accomplishments of the human mind; it makes possible planning, reasoning, problem

solving, reading, and abstraction. Of course some minds accomplish these goals with

more success than others. (italics added)

The chapter goes on to describe research that has shown that people who have a large-

capacity working memory are often better at cognitive processes such as reading and

reasoning, and that this is also refl ected in higher scores on intelligence tests.

One of the pioneering studies linking working memory and cognitive processes

is a study of reading by Meredyth Daneman and Patricia Carpenter (1980). The rea-

son Daneman and Carpenter’s experiment is considered a “classic” is because of their

insight that tests such as the digit span test used to measure the capacity of STM (see

page 125) are not useful for measuring the capacity of working memory. They reasoned

that any test of working memory capacity has to involve a dynamic process more like

what goes on in everyday cognitions such as reading and solving problems.

The test they developed, called reading span, was designed to measure both the

storage and processing functions of working memory. It accomplishes this by measur-

ing the maximum number of sentences that a person can read while simultaneously

● FIGURE 5.28 Results of the Vogel et al.
(2005) experiment. The key fi nding is that
performance is about the same for high- and
low-capacity participants when only the red
rectangles are present (left pair of bars), but
although adding the two blue rectangles has
little eff ect for the high-capacity participants, it
causes an increase in the response for the low-
capacity participants (right pair of bars). (Source:
Based on E. K. Vogel, A. W. McCollough, & M. G. Machizawa, “Neural
Measures Reveal Individual Differences in Controlling Access to
Working Memory,” Nature 438, 500–503, 2005.)

High

2 red 2 red +

2 blue

Low High Low

0

–2 V

–1

ERP response

Operation

Span

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