accounts claim that there is a limited-capacity working memory—a place that
holds the currently activated information and the program for manipulating it.
More discussion of information processing can be found in the introductory
chapter.
The contribution of information processing to the study of intelligence is its
claim that any or all of these components of cognition could be the basic and
essential source of individual differences in intellectual activity (e.g., Carroll,
1983; Jensen, 1982; Vernon, 1983; Sternberg, 1985; Hunt, 1983; Pellegrino &
Glaser, 1979). Some people might be more intelligent than others because they
can more quickly and efficiently process stimulus input, retrieve information
from memory, or transform information from one form into another.
An Example of Research Based on Information Processing: Inspection Time The in-
formation processing perspective has produced a variety of experimental para-
digms for measuring the speed and efficiency with which people can carry out
any component of cognitive processing. In the typical information processing
experiment, researchers use established experimental paradigms to obtain from
each subject an estimate of how quickly or efficiently the subject can execute
one of the components, and then measure the correlation between that estimate
and the subject’s score on an IQ test.
One task that has been studied extensively is called theinspection time task
(Deary & Stough, 1996). In a typical version of this task, subjects are given two
parallel vertical lines joined at the top by a horizontal line. One of the vertical
lines is longer than the other. An example of a stimulus used in the inspection
time task is provided in figure 36.1. Over a series of trials the longer line is
presented on the left side about as often as it is presented on the right. Subjects
must identify which is the longer line and can take as long as they want to
make the decision. The task is made difficult by limiting the amount of time the
stimulus is exposed to the subjects; that is, the inspection time is kept brief. The
range of exposure durations is usually between 100 milliseconds to less than
around 10 milliseconds. Any given subject’s inspection time is usually ex-
pressed as the stimulus duration necessary for the subject to reach a given ac-
Figure 36.1
A typical stimulus used in the inspection time task. From a very brief exposure to such a stimulus,
subjects must decide whether the left or the right vertical line is longer. (See Deary and Stough,
1996.)
Individual Differences in Cognition 785