Chapter 7 Overview

Attention and Scene Perception

When this page first loads, you will see ten reddish circles in a circular arrangement near the middle of the screen. Click the START button in the top-right corner. Five of the circles will flash purple, then all ten will begin wandering randomly around the screen. Four seconds later, they will stop. Do you remember which five circles were flashing? Click on any of the circles that you were able to track, then click SHOW in the upper right to reveal which circles were actually cued.

Click the START button again and try tracking only one of the flashing circles. You should find this very easy. Tracking two circles at once should also be fairly simple, but once you start tracking three or more, the task will become quite a bit more difficult. With a lot of practice, you might actually be able to track all five flashing circles with some success, but you can see how difficult it is.

What do you have to do to track the circles? If you’re only trying to track one, you can simply fixate your gaze on it and move your eyes along with the circle. But to track more than one circle, eye movements will not be enough. Multi-element tracking requires sustained visual attention.

Attention is a general term for mechanisms that select certain stimuli for further processing. Just as you can’t possibly track all ten of the moving circles in this demonstration, imagine trying to simultaneously process every single object that appears in your visual field as you, for example, emerge onto a crowded street from a subway station. Attention mechanisms allow you to efficiently deal with this constant barrage of information by tackling selected portions of the visual field one by one.

The main thrust of this chapter deals with how vision scientists have used clever psychophysical techniques to explore various forms of attention. You can sample many of these techniques here, in the activities on Attentional Cueing, Visual Search, The RSVP Paradigm, and The Attentional Blink and Repetition Blindness (see also the essay on Attentional Capture).

The latter portion of the chapter discusses the related topic of scene perception. As the activities on Change Blindness and The Attentional Bottleneck demonstrate, when attention is limited we are surprisingly poor at picking up details, and sometimes even central elements, of visual scenes. The essay on Boundary Extension shows one way in which how, even when we study a scene for a long time, our memory for the scene is far from perfect. Finally, the essay on Balint Syndrome discusses how certain kinds of brain damage can severely limit the number of objects attended to within a scene.

Once you’ve read the chapter in the textbook and done the activities here, use the study aids (Study Questions, Flashcards, and Chapter Summary) to review.