Thursday, December 6, 2007

Of course you'd say that; you have the brainpan of a stagecoach tilter

Dr. Daniel Amen flogs neuroimaging for presidential candidates in the LAT.

Amen's no stranger to dubious endorsements of neuroimaging techniques - he's made a name for himself selling SPECT scans as a diagnostic tool for everything under the sun.

Amen's proposal is little more than phrenology updated for the 21st century. Indeed, the core scientific truth from which they both extrapolate is the same - that certain aspect of mental function are localized to certain areas of the brain. And they both go wrong in by attributing way more significance to the extent to which size or blood flow respectively serves as a predictor of function. Functional imaging (which uses radiotracers to measure the blood flow in different areas of the brain) is a useful research tool, since it reveals what areas of the brain are active at a given time and may someday find its way into clinical use (SPECT, for example, may be useful for diagnosing Alzheimer's, but it has its limitations. Functional neuroimaging does a good job of revealing what low-level neurological activity is going on (ex recognizing faces, language processing, feelings of disgust) at a given time, but complex behaviors generally cannot be reduced to a distinguishable pattern of activation and while differences in activation can be observed between populations with clear psychological or neurological differences (ex the lack of emotional reaction to freightened faces by psychopaths, the impaired language processing of sufferers of the various forms of aphasia), it has not been demonstrated to be a reliable tool for classifying compared to behavioral observation. Amen wants us to believe that despite this, neuroimaging of presidential candidates could be used to measure personality traits relevant to their performance in office. If you believe that, I have a diagnostic brain scan to sell you...

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