19 April 2010

Lemme see your war face!

ResearchBlogging.orgPeople in the military are highly trained to perform at high levels under horrible situations. It’s a reasonable hypothesis to think that these individuals would have different cognitive performance and brain activity than civilians.

A new study by Paulus and colleagues tries to get inside the brains of some of these military personnel using the darling technique of the moment for humans, functional magnetic resonance imaging (fMRI).

The authors recruited veteran Navy SEALs, and compared their behavioural and neural responses to emotional faces. They showed pictures of people who were showing angry (maybe a little like the one shown right), scared, or happy faces, and the subjects had to match the emotion shown to another picture on a screen. The subjects did this task while the research team was scanning their brains.

Now, the thing of it is, there is no explicit prediction about what sorts of behaviour is expected between the soldiers and the controls. That’s a shortcoming of this study, because the authors did find significant differences between the SEALs and controls. But the SEALs were...

Slower. Sometimes.

Wait. What?

Now, “slow” is not the first thing you’d expect a Navy SEAL to be. But they were only slower to match fearful and happy faces. Response time of SEALs to angry faces? Same as control.

Now, here is perhaps another oddity of this study. Paulus and company describe several differences in neural activation of the two groups, related to the insula. An interesting finding is greater neural activation in the SEALs in response to angry faces. They argue that this suggest the military personnel are using greater neural processing to stimuli related to being in combat, implying that “angry” faces are more relevant to someone in the military than other faces.

None of the neural differences seem to relate to the differences in response time they found. Without any sort of correlation, the fMRI findings are facts in isolation. To their credit, the authors admit this. They chalk up the few differences between the test groups as perhaps due to a small sample and the nature of the task. They don’t much hint, though, at how they might test this “increased neural processing power” hypothesis. Or, for that matter, how they might expect that extra brainpower to manifest itself in behaviour.

The title claims to show “enhanced threat detection” in the SEALs. But “detection” is a description of behaviour, not brain activation. If SEALs do not outperform controls on the behavioural task, then the title is a bit misleading.

Additional: Neuroskeptic also put up an analysis of this paper, like 5 minutes, after I’d put up mine.


Paulus, M., Simmons, A., Fitzpatrick, S., Potterat, E., Van Orden, K., Bauman, J., & Swain, J. (2010). Differential brain activation to angry faces by elite warfighters: Neural processing evidence for enhanced threat detection. PLoS ONE, 5(4): e10096. DOI: 10.1371/journal.pone.0010096

1 comment:

SleepRunning said...

You review of the research is more useful than Neuroskeptic. That blog seems mainly focused on rhetoric - which does get readers.

Our comment to them was:
"Understand the appeal of faux-skepticism and easy dismissal of stuff...a lot easier to process, less brain power required, but also pretty dull.

Being skeptical abt this post’s skepticism...
- It points out the preliminary and partial nature of the study….that's trivial. Neuroscience and it's technologies are imperfect and new. You're not basing your whole blog on that blinding insight, we hope!

More clever, but also trivial, is the rhetorical trick of damning the authors for not studying what you imply they should have!? Then the results not addressing the issues you wanted addressed.

C’mon, how about a lil more brain power here!"