THE PHENOMENON OF BRAIN PLASTICITY 37oretically be mapped to those systems, and, if socioeconomic status is taken
to be a more or less stable characteristic of a person, the categorization of
research subjects by ses. In many of the aforementioned studies, the re-
search subjects are also ‘ethnically matched’ so that African American poor
children are compared to African- American middle- class children, with no
other ethnicities represented at all.^24 This means the research is curiously
both racialized (every poor subject is Black) and race- blind (only class is
measured), even while other categorizations are created (see Hackman et
al. 2012 on ses differences by both gender and neighborhood). There is also
the conduct of experiments that test those subjects and the enactment of
statistical correlations of test scores, images, and measures. These are not
solely representational but also material practices, making cuts to enact
particular differences.
In some studies, for example, behavioral differences between classes of
research subjects are elicited through experiments using cognitive tests. In
others, neural differences are elicited through technologies such as fmri^
and event- related potentials (where electrodes placed on the scalp measure
voltage changes coming from neurons, and averages of those measures are
timed with specific behavioral tasks). In the first case, behavioral differences
are sometimes interpreted as proxies for neural difference where no direct
neural difference is examined, as when a test score is thought to indicate
brain capacities in specific systems (Farah, Noble, et al. 2006; Farah, Shera,
et al. 2006). In the second case, neural differences are deemed significant
whether or not differences in behavioral measures are found. For example,
some studies report different patterns of neural activity between research
subjects with low ses and those with middle ses during the execution of
certain cognitive tasks when there is no measurable difference in how well
the research subjects perform the task (D’Angiulli et al. 2008; Hackman
and Farah 2009; Kishiyama et al. 2008; Stevens et al. 2009). Another study
reports neural difference without measuring a task at all (Tomarken et al.
2004). Despite behavioral parity or the absence of behavioral difference, in
these studies neural disparities are deemed significant and interpreted to
suggest differences in cognitive capacities. Using the logic of reverse infer-
ence, neural patterns are interpreted as evidence of less efficient use of neu-
ral resources (D’Angiulli et al. 2008; Stevens et al. 2009) or even, absent any
symptoms, pathology or brain damage (Kishiyama et al. 2008; Tomarken