98 • CHAPTER 4 Attention
Before you conclude that missing some of the things in the environment is a serious
problem, let’s return to a cognitive capacity we discussed in Chapter 3—the cognitive
system’s ability to “fi ll in” the blanks because of our knowledge of regularities in the
environment (see Chapter 3, page 63). As you approach an intersection with four-way
stop signs, you may not be aware of the exact kind of car that is approaching from the
left, or that it has a Florida license plate, but you do know that a car is approaching and
have had enough experience driving to know that you need to check to see if the other
car is slowing down and to be ready for the possibility that the other car might not stop.
Thus, your knowledge of things that normally occur in the environment enable you to
predict what is likely to be happening “off to the side” without being aware of every
detail of the situation.
Another factor that helps you deal with unattended stimuli in the environment is
that potentially dangerous stimuli, such as traffi c, other people, or a dog running across
your path, often move or produce sound. This movement or sound causes you to direct
your attention to the stimulus, so you can react to it.
Reacting to movement or sound is often an automatic process. Something moves
off to the side and, without thinking, you automatically look toward it. A car backfi res,
and you turn your head to determine where the sound came from. Automatic attrac-
tion of attention by a sudden visual or auditory stimulus is called exogenous attention.
This is different from the type of attention that occurs when you consciously decide to
scan the environment, perhaps to fi nd a specifi c stimulus or just to keep track of what
is going on. This consciously determined attention is called endogenous attention. Both
types of attention can involve overt attention, shifting attention by moving the eyes
(Carrasco, 2010; Henderson, 2003).- Describe the Schneider and Shiffrin divided attention experiments. Compare
the stimulus conditions for consistent and varied mapping conditions, and how
these different conditions result in automatic or controlled processing. - What conclusions can be reached from the results of experiments testing the
ability to drive while talking on a cell phone? What are some of the differences
between a driver talking to a passenger and a driver talking on a cell phone? - Describe the following evidence that attention is necessary for perception:
inattentional blindness experiment; “basketball” experiment; change detection
experiments. Be sure you understand what is preventing attention from being
directed to parts of a display or scene in each of these experiments.
Overt Attention: Attending by Moving Our Eyes
The shifts of attention that occur in overt attention are accompanied by eye movements.
Why do we need to move our eyes to shift attention? We began answering this question
in the previous section in which we described inattentional blindness and change detec-
tion. Both of these cases indicate that we miss objects or changes in the environment
that we are not paying attention to, but when people are told where to look in a scene,
they can detect the objects or changes they had previously missed.
Inattentional blindness and change blindness are therefore situations in which
attention and perception are closely linked. We can perceive things we pay attention to,
and we miss things we don’t pay attention to. This section continues this theme by spe-
cifi cally considering the connection between eye movements, attention, and perception.EYE MOVEMENTS, ATTENTION, AND PERCEPTION
The link between eye movements, attention, and perception is illustrated by the follow-
ing demonstration.TEST YOURSELF 4.2
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