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From Scanner to Sound Bite:Issues in Interpreting and Reporting Sex Differences in the Brain


From Scanner to Sound Bite: Issues in
Interpreting and Reporting Sex
Differences in the Brain
Current Directions in Psychological
Science
19(5) 280-283
ª The Author(s) 2010
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DOI: 10.1177/0963721410383248
http://cdps.sagepub.com
Cordelia Fine
Centre for Agency, Values and Ethics, Macquarie University, and Department of Psychological Sciences,
University of Melbourne
Abstract
Neuroimaging research is yielding reports of sex differences in the brain. Yet the likelihood of spurious findings of sex differences,
the teething problems of new technology, the obscurity of the relation between brain structure and psychological function, and
difficulties inferring mental states from neuroimaging data all require us to be considerably cautious in interpreting such results.
Unfortunately, these issues are often overlooked in popular accounts. Together with a tendency for people to regard
neuroscientific information as more scientific than behavioral data, and as indicative of male and female ‘‘nature,’’ these issues
point to the worrisome possibility of public misunderstanding of what contemporary neuroscience tells us about gender.
Keywords
neuroimaging, gender, science communication, neuroethics
For as long as there has been brain science there has been both
scientific and popular interest in male–female differences and
their psychological consequences. For example, 19th-century
scientific opinion held that women’s intellectual inferiority
could be attributed to their smaller and lighter brains—a fact
that was widely known among the Victorian public as the
‘‘missing five ounces’’ of female brain (see Russett, 1989).
Today, the weighing scales and other crude methodologies of
the Victorian brain scientists have been supplanted by sophis-
ticated neuroimaging techniques that give unprecedented
access to structural details of the brain and patterns of neural
activity. Yet there remains cause for skepticism regarding
neuroscientific claims about sex differences and concern over
the way such information is reported to, and interpreted by, the
public. In this article, I lay out four scientific issues arising
from the production and interpretation of ‘‘facts’’ about sex
differences in the brain, then discuss how these issues are
overlooked and exacerbated when neuroscience findings are
disseminated in the popular media and digested by the public.
To illustrate these points, I use as an example a long-
standing and influential claim about male–female brain
difference. The greater male lateralization (GML) hypothesis
proposes that males, compared with females, are more strongly
left hemisphere dominant for language processing and right
hemisphere dominant for visuospatial processing. Females,
by contrast, tend to engage both hemispheres for these tasks
and, in keeping with the female brain’s supposedly more
interhemispheric functioning, are claimed to have a relatively
larger corpus callosum (the bundle of neurons that connects the
two hemispheres). In both academic and especially popular
work, these structural differences are proposed to have
psychological implications.
Production: The Problem of
Spurious Results
When neuroscientists, in a single experiment, establish a ‘‘sig-
nificant difference’’ between the sexes, does this reflect a real
and reliable sex difference? Because sex is a primary and
ubiquitous social category, classifying participants by sex is
obvious, easy, and may be done by default (Kaiser, Haller,
Schmitz, & Nitsch, 2009). However, since by convention
researchers declare a difference to be ‘‘significant’’ if there is
no more than a one in 20 probability that it occurred by chance,
if 20 researchers routinely test for sex differences, then even if
there is no real difference between the populations, one
Corresponding Author:
Cordelia Fine, Department of Psychological Sciences, University of Melbourne,
Victoria 3010, Australia
E-mail: cfine@unimelb.edu.au
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