88 • CHAPTER 4 Attention
available for processing other stimuli that may be present. This can occur even if the
person does not intend to process these other stimuli. For example, a person is sitting in
her dorm room listening to music, which uses only a portion of her cognitive resources,
so the voices of people talking in the hall intrude even though the person would rather
not hear them. Stimuli such as talking in the hall are task-irrelevant stimuli that have
made use of some of the person’s remaining cognitive resources.
Figure 4.7b shows a situation in which all of a person’s cognitive resources are
being used by a high-load primary task. When this occurs, no resources remain to
process other stimuli, so these stimuli can’t be processed. This means that the person’s
attention is totally focused on the primary task. Such a situation might occur when a
person is sitting in his dorm room concentrating intensely on a particularly diffi cult
homework problem. The person is concentrating so hard that he is devoting all of his
cognitive resources to the task, so he is only vaguely aware of the people talking in the
hall.
We will now describe a laboratory test of these ideas, which involves a task called
the fl anker compatibility task.METHOD Flanker Compatibility Task
The fl anker compatibility task is a task in which participants are told to carry out a task that
requires them to focus their attention on specifi c stimuli and to ignore other stimuli (Eriksen &
Eriksen, 1974). An example is shown in ● Figure 4.8, in which the task is to selectively attend to
the target in the center position (A in this example) and to press the “z” key if A or B is presented
in the center and the “m” key if C or D is presented. They are told to ignore the “fl anker” stimuli
that are presented on either side because these are task-irrelevant stimuli that aren’t needed
for the primary task. One target stimulus is presented in the central position on each trial, and
this target is fl anked on either side by A, B, C, D, or X.
In Figure 4.8a, the fl ankers are associated with the same response as the target (pushing
the z key is the response for both). These fl ankers (B’s) are therefore called compatible fl ank-
ers. In Figure 4.8b, the fl ankers (C’s) are associated with a diff erent response (pushing the m
key) than the target; these are called incompatible fl ankers. In Figure 4.8c, the fl ankers (X) are
neutral; they aren’t associated with any response.
Because pushing a key in response to an easily visible target is easy, this task wouldn’t use
all of a person’s cognitive resources, so some cognitive resources would remain available, as in
Figure 4.7a. If this is so, we would expect that the fl anker stimuli will be processed even if the
participant doesn’t intend to process them.
Typical results for a fl anker compatibility experiment,
shown in the right column, indicate that this is the case. When
participants try to respond to the target as quickly as pos-
sible, they typically respond more slowly when incompatible
fl ankers are present (as in b) than when neutral fl ankers (c) or
compatible fl ankers (a) are present. This occurs because the
incompatible fl anker elicits a response that is diff erent from
the one that is required for the target and therefore competes
with the response that the participant is supposed to make
to the target. The fact that the fl anker has this eff ect demon-
strates that even though participants were told to ignore the
fl ankers, they still processed information from them.We will now consider an experiment similar to the
one above, but in which the load of the task is varied
(Lavie, 2005; Lavie & Cox, 1997). In this experiment,
a target stimulus appears somewhere in a ring of six● FIGURE 4.8 Stimuli for fl anker compatibility tasks. A is the
target in these examples. (a) A task with compatible fl ankers
(like B) results in a fast response to A. (b) Incompatible fl ankers
(like C) result in the slowest response time to A. (c) Neutral
fl ankers (like X) result in an intermediate response speed.B A B Compatible Fastest response
to targetC A C Incompatible Slowest response
to targetX A X Neutral(a)(b)(c)TargetIntermediate response
to targetSTIMULUS FLANKERS TYPICAL RESULTCopyright 2011 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.