consider each white symbol one by one, orserially.This experience is compa-
rable to finding something in your environment that is both red and a circle.
Preattentive processing allows you swiftly to find things that are red or things
that are circles—preattentive processing allows aguided searchof your envi-
ronment (Wolfe, 1992). At that point, however, you need to attend to each ob-
ject individually to determine whether it fits theconjunctionof the two features
round and red.
Researchers recognize the difference between a parallel and a serial search by
determining how hard it is to find a target as a function of the number of dis-
tractors. Suppose we ask you to find a white T in a display with five black T’s
(as in part C of figure 7.13) versus a display with 34 black T’s (as in part A).
Because you can carry out this task in parallel, it will take you roughly the
same amount of time to find the white T in each case. On the other hand, when
you move from part B to part D of this figure, you can sense that you’re much
quicker to find the white T in D. You have to attend to each white element
Figure 7.12
An example of overlapping figures. Cover the right part of the figure with a piece of paper. Look at
the pictures of overlapping colored shapes on the left side of the figure. Try to attend to the red
shapes only and rate them according to how appealing they seem to you. Next, cover the left side of
the figure and uncover the right side. Now test your memory for the red (attended) figures and the
blue and green (unattended) figures. Put a check mark next to each figure on the left you definitely
recall seeing. How well do you remember the attended versus the unattended shapes?
154 Philip G. Zimbardo and Richard J. Gerrig