15
Critical Thinking: Needed Now More Than Ever
Brain-scanning methods, which every psychology student learns about, have revolu-
tionized medicine and have led to an explosion of research, not only in medicine and
cognitive neuroscience but also in many other fields. The number of published studies
using functional MRI jumped from just 10 in 1991 to 864 in 2001 (Illes, Kirschen, &
Gabrieli, 2003) and thousands of facilities now use fMRI for research and assessment.
Researchers are using brain scans to study memory, racial attitudes, moral reasoning,
decision making, the anticipation of pain, spiritual meditation, sexual arousal, you name
it. They are using scans to compare adolescent and adult brains, and the brains of schizo-
phrenia patients with the brains of mentally healthy people. In the new applied field of
neuromarketing, they are even identifying brain areas that are activated while people watch
TV commercials or political ads.
So, what’s the problem? The answer is that every revolution in science initially evokes
uncritical zeal, and this one is no exception. As one team of psychologists who use MRI
technology in their research wrote, “Just because you’re imaging the brain doesn’t mean
you can stop using your head” (Cacioppo et al., 2003). And when we use our heads, we
find that not all the findings reported in the popular press or even scientific journals are
based on good science and critical thinking, no matter how fancy or impressive the tools
that produced them.
Some of the problems are methodological. The beautifully colored scans we show our
students and that appear all the time in newspapers and magazines and online can convey
oversimplified and sometimes misleading impressions (Dumit, 2004). For example, by
manipulating the color scales used in PET and MRI scans, researchers can either accentu-
ate or minimize contrasts between two brains. Small contrasts can be made to look dra-
matic, larger ones to look trivial. An individual’s brain can even be made to appear
completely different depending on the colors used.
It’s not just the colors that are arbitrary. The researcher uses certain algorithms to con-
vert numerical data to a visual representation, and in doing so, sets criteria for deciding
where the boundary lies between, say, high neural activity and moderate neural activity.
There may be good reasons for setting the criteria at certain points, but for the most part
these assignments are arbitrary, and they will influence the results and the graphic image
of those results. As William Uttal observes in his provocative book The New Phrenology:
The Limits of Localizing Cognitive Processes in the Brain (2001), one researcher may draw
the line conservatively, and thus obscure evidence of localized activity, whereas another
may draw the line more liberally, and thereby produce apparent localizations that are
actually mere artifacts.
Other problems with brain scans are conceptual. For example, although brain areas are
fairly well defined, the cognitive processes and operations that researchers are attempting
to associate with these areas typically are not. You do not have to be a behaviorist to
acknowledge that one of psychology’s toughest challenges has been to define, to everyone’s
agreement, just what it is we are trying to study. The definition of an emotion such as
happiness, or a mental operation such as remembering a past event, often depends on how
a researcher happens to measure the construct in question. Most psychological constructs,
once we get beyond simple sensory and motor responses, are denoted by a single word or
term but actually cover an intricate and complicated series of operations or processes. How
do you establish “where” in the brain happiness is processed if researchers cannot agree on