Are “pictures” of the brain so persuasive that they can sway juror decision making? Even though the credibility of the medical experts has to be factored in, many people believe that when you include brain scan photos (as opposed to bar charts or topographical maps for example) the viewer is more persuaded. Even though there isn’t a chance in the world that an average juror can make sense of the image.

So, the current researchers decided to look at the effect, if any, of neuroimages using a fact pattern of a capital murder case. They were trying to sort out whether it is useful to focus mitigation arguments on neuroimaging evidence, since it could “create the impression the defendant is ‘damaged goods’ and beyond repair.”

The researchers presented the facts of a murder along with evidence (included in nearly all capital trials) of the likelihood of future dangerousness and evidence about the psychiatric condition of the defendant. They divided participants into 3 conditions:

The first group was told the defendant was psychotic.

The second group was told the defendant was psychotic and was given the results of neuropsychological testing discussing damage to the defendant’s brain (specifically, the frontal lobe).

The third group was given the diagnostic information and the test results but also shown color photos of “structural and functional scans of the defendant’s brain” and given descriptions of likely consequences with this sort of damage to the brain.

The researchers expected that the more information participants were given, the less they would choose the death penalty IF the defendant was adjudged to be at low risk for future violence. And they were wrong.

When mock jurors were provided only a diagnosis, and were told the defendant had a high risk of future violence, they were overwhelmingly more likely to give a death sentence (65% voted for death penalty) than other mock jurors. When they were given additional information (either a psychological testing summary or the testing summary with neuroimaging evidence), their imposition of the death sentence dropped dramatically (down to 12% voting for death penalty). If jurors assessing these ‘dangerous’ defendants were given all three forms of information, the death penalty was selected only 8% of the time.

Oddly, low risk of dangerousness only affected those jurors who were only given the diagnosis (but no supportive test data or images). ‘Diagnosis only’ mock jurors assigned the death penalty about 17% of the time (down from 65%), while diagnosis plus testing mock jurors chose the death penalty about 21% of the time and mock jurors receiving all three types of evidence chose the death penalty about 14% of the time (essentially the same as the ‘high risk of violence’ condition).

The researchers concluded that with high risk for future violence defendants, both neuropsychological testing and neuroimaging evidence reduced the likelihood jurors would choose the death penalty. Rather than being ‘aggravating’, this additional evidence was truly mitigating in the case of the high-risk-to-violently-reoffend defendant.

Our view is that this is consistent with what is frequently seen in juror decision-making: Jurors are much more comfortable accepting a high-risk proposition if they are comforted that they have a valid reason for doing it.  This is most clearly seen in the high risk group, where they needed to be assured there is ‘scientific evidence’ that the defendant was impaired, not merely that the defense found an expert willing to make that claim.  It also suggests that in the population used in the study, there were about 15-20% who were in favor of the death penalty regardless of mitigating scientific  evidence.

It’s important to note that the neuropsychological testing results mitigated almost as much as the testing results plus the brain pictures. The verbal description alone (or verbal picture if you will) persuaded jurors. The researchers say it is possible that any additional information pertinent to the defendant’s condition ‘personalizes’ the defendant for jurors and thus may prove mitigating. We go with the former idea, as it seems unlikely that a psychological test profile or a description of neuroimaging studies causes anyone to become more ‘personal’. The jurors simply want reassurance that they are working off more than one person’s opinion.

For the practitioner, this says you don’t need bells and whistles [like brain scans] to successfully mitigate. But you do need solid and scientific information, well-presented using language and examples jurors can understand. That testimony can save a life.

Greene, E., & Cahill, B. (2011). Effects of Neuroimaging Evidence on Mock Juror Decision Making Behavioral Sciences & the Law DOI: 10.1002/bsl.1993

Image 

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Joanna Fraser, a forensic sciences researcher at the University of Abertay, Dundee, said: “The research uses fine layers of metals to display fingerprints people may have left on fabrics, something which is far harder to do with soft surfaces. The technique has been around since the 1970s and is used on many surfaces but was never widely used on fabrics.

“We take these fabrics, place them in a vacuum chamber, then heat up gold to evaporate it and spread a fine film over the fabric. We then heat up zinc, which attaches to the gold where there are no fingerprint residues. This helps reveal the fingerprint — where contact has been made we see the original fabric, where there was no contact we’re left with the grey colour of the metal film.”

She added: “One way of explaining it is like a photographic negative, where colours show up as their opposites. Here the fingerprint ridges show through as clear fabric, but where there are no ridges we see the distinctive grey colour of the metal.

“Previously it had proved difficult to reveal a clear fingerprint on fabric, but we’ve shown that this is now possible. This is great, but the challenge is to develop this further and confirm its effectiveness.”

So, for example, if your favorite jeans had two handprints on the butt—maybe you were shoved off the balcony as opposed to jumping. Or—if scientists find handprints or fingerprints on your favorite jeans—they know to target those areas for further DNA evidence.

There is nothing like a good pair of jeans.  Overall, though, I can’t say I’m going to sleep better for knowing this.

 
Fraser J, Sturrock K, Deacon P, Bleay S, & Bremner DH (2010). Visualisation of fingermarks and grab impressions on fabrics. Part 1: Gold/zinc vacuum metal deposition. Forensic science international PMID: 21126838

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Researchers are using brain scans for everything! They’re checking for brain activity in dead fish. They’re even putting people in brain scan machines with snakes which is just nasty.

Thankfully, two law professors are offering pretty straightforward information to help us weed through what makes sense and what doesn’t as more and more information on brain scans and neurolaw comes forward. Both pieces are available at no charge via SSRN:

1. Cherry-Picking Memories: fMRI-Based Lie Detection in the U.S. Courts by Jonathan R.H. Law.

This article discusses fMRI-based research techniques in the context of US federal courts. The fMRI is seen as providing data that is more prejudicial than probative. The authors then propose an approach to the Daubert standard and recommend that US courts wait a while before incorporating fMRI data into evidence.

2. Brain Imaging for Legal Thinkers: A Guide for the Perplexed by Owen D. Jones, Joshua Buckholtz, Jeffrey D. Schall, and Rene Marois.

This article provides an introduction for legal professionals to brain imaging. It describes the techniques and methods used by fMRIs and then offers a tutorial on reading and understanding a brain-imaging study. Finally, the articles shares information on how to avoid misunderstanding brain images and how to recognize when others are misusing brain images in legal contexts.

And, a third piece has been put out entitled: A Judge’s Guide To Neuroscience: A Concise Introduction with multiple authors. This one is put out by the Law and Neuroscience Project and is written especially for judges. You may find this one the most user-friendly in terms of vocabulary but all three are worth a read if you would like to understand the shifting sands of the neurolaw area a bit better.

Read them. We will too. Then come back for more updates on Neurolaw.

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