HOW THE BRAIN MAKES POTENTIAL 193survey in 2007 indicated that 43 percent of participants found the experi-
ence upsetting, with 33 percent reporting side eff ects like headaches.
Children in par tic u lar are likely to be restless. As Michael Rutter and
Andrew Pickles warn, “motion artifacts... can lead to quite misleading
conclusions about the interconnectivity across brain regions.”^28
Moreover, when the participant is confi ned in the cylinder, it is dif-
fi cult to pres ent him or her with realistic cognitive tasks and evoke mean-
ingful responses. For example, speech, which involves muscle movements,
distorts the readings. In other words, fMRIs can be quite accurate as in-
dices of categorical disease or trauma states. But they need to be applied
more carefully for describing normal variation.
As a consequence, it is quite likely that what are read as cognitive dif-
ferences are actually aff ective/emotional in origin. As Hadas Okon- Singer
and colleagues warned in a review, the distinction between the emotional
and the cognitive brain is fuzzy and context dependent. Th ere is compel-
ling evidence that brain regions commonly associated with cognition,
such as the dorsolateral prefrontal cortex, also play a central role in emo-
tion. Furthermore, they go on— and as I mentioned above— “putatively
emotional and cognitive regions infl uence one another via a complex
web of connections in ways that jointly contribute to adaptive and mal-
adaptive be hav ior. Th is work demonstrates that emotion and cognition
are deeply interwoven in the fabric of the brain.”^29
Th ere are other doubts arising from the fuzziness of scans. A study in
2014, for example, compared a variety of MRI scans of axonal projections
in monkey brains with accurate maps drawn from standard anatomical
methods. It was concluded that none of the scan methods demonstrated
high anatomical accuracy.^30
Fi nally, as might be suspected in the light of comments mentioned
in chapter 1, there is poor replicability and evidence of reporting bias in
which only positive results are published. So Rutter and Pickles also
warn that, while “brain imaging constitutes a valuable tool... so far, its
achievements do not live up to the claims and its promise.”^31
In consequence, results have been inconsistent. Some have shown pos-
itive correlations between cortical thickness and IQ, others have been
negative. As an analy sis in 2015 concluded, “ Th ese studies have produced
inconsistent results, which might be partly attributed to methodological
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