The Brain Scan Appeal

The MRI scan on the left reveals a series of anatomical abnormalities linked to violent behavior and commonly found in the brains of psychopaths. Note how different the psychopathic brain is from the normal brain on the right.

Okay, I totally made that up. But if you’re like most people, you probably thought my description had some credibility. Why? Because I provided you with a neuroscientific explanation and dazzling photos of the inner workings of the brain.

Recent articles on the use of brain imaging techniques as evidence in criminal trials (in New Scientist, Discover, NPR, and Nature) have all pointed out many potential problems: from the practical (the science is poorly understood and not appropriate for forensic evidence), to the moral (we shouldn’t reduce a complex human agent into a series of image outputs). But further problems appear if we shift the spotlight from the defendant’s brain to another player in the courtroom — the juror.

Evidence suggests that brain images and neuroscientific explanations may unduly influence a juror’s decision. A Colorado State University study concluded that people interpret data as more scientifically credible when it includes images from brain scans (as opposed to other visuals like charts and graphs). Another study, from a group at Yale University, found that people are more convinced by a neuroscience-infused explanation, even when the supplemental information is completely irrelevant. In other words, the more random brain scans and neuroscience terminology you can pack into your argument, the more likely you are to win your case.

So next time you find yourself staring at the image of another person’s brain, just keep in mind how it may be affecting yours.