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148   Philip G. Zimbardo and Richard J. Gerrig

                     Gestaltists. Modern researchers often try to understand how sources of
                     information are combined to arrive at a perceptual interpretation of the
                     world. These researchers compare the process of perception to conceptual
                     problem solving (Beck, 1982; Kanizsa, 1979; Pomerantz & Kubovy, 1986;
                     Rock, 1983, 1986; Shepp & Ballisteros, 1989). We will see some of their
                     insights in the remaining sections of this chapter.
                     .  What are the properties of the physical world that allow youto perceive? This
                     question makes contact with Gibson’s theory. His central insight was that
                     the world makes available certain types of information—and your percep-
                     tual apparatus is innately prepared to recover that information. Gibson’s
                     research made it clear that theories of perception must be constrained by
                     accurate understandings of the environment in which people perceive.
                  We now begin our discussion of perceptual processes by considering what it
                means to select, or attend to, only a small subset of the information the world
                makes available.


                Attentional Processes
                We’d like you to take a moment now to find ten things in your environment
                that had not been, so far, in your immediate awareness. Had you noticed a spot
                on the wall? Had you noticed the ticking of a clock? If you start to examine
                your surroundings very carefully, you will discover that there are literally
                thousands of things on which you could focus your attention. Generally, the
                more closely you attend to some object or event in the environment, the more
                you can perceive and learn about it. That’s why attention is an important topic
                in the study of perception: your focus of attention determines the types of
                information that will be most readily available to your perceptual processes.
                As you will now see, researchers have tried to understand what types of envi-
                ronmental stimuli require your attention and how attention contributes to your
                experience of those stimuli. We will start by considering how attention func-
                tions to selectively highlight objects and events in your environment.

                Selective Attention
                We began this section by asking that you try to find—to bring into attention—
                several things that had, up to that point, escaped your notice. This thought
                experiment illustrated an important function of attention: to select some part
                of the sensory input for further processing. Let us see how you make decisions
                about the subset of the world to which you will attend, and what consequences
                those decisions have for the information readily available to you.
                Determining the Focus of Attention  What forces determine the objects that be-
                come the focus of your attention? The answer to this question has two compo-
                nents, which we will call goal-directed selection and stimulus-driven capture
                (Yantis, 1993). Goal-directed selection reflects the choices that you make about
                the objects to which you’d like to attend, as a function of your own goals. You
                are probably already comfortable with the idea that you can explicitly choose
                objects for particular scrutiny. Stimulus-driven capture occurs when features
                of the stimuli—objects in the environment—themselves automatically capture
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