Monday, December 13, 2010

The brain isn’t going to take it lying down

The brain may manage anger differently depending on whether we’re lying down or sitting up, according to a study published in Psychological Science that may also have worrying implications for how we are trying to understand brain function.

Anger experiments that have measured electrical signals from the brain (using EEG) or that have altered neural activity with magnetic pulses (using TMS) have found that the left frontal lobe is more active than the right, but studies using fMRI functional brain scans have found no differences.

Psychologists Eddie Harmon-Jones and Carly Peterson wondered whether the brain might be working differently in EEG and TMS experiments because the participant is usually sitting upright, while in fMRI, the person is usually lying flat on their back.

If this seems like a trivial distinction as far as emotion is concerned, it actually has some sound theory behind it. A field of study called 'embodied cognition' has found lots of curious interactions between how the mind and brain manage our responses depending on the possibilities for action.

For example, we perceive distances as shorter when we have a tool in our hand and intend to use it, and wearing a heavy backpack causes hills to appear steeper.

Anger is a prime example where we feel motivated to ‘do something’. In the sitting position we’re much more ready to approach whatever’s annoying us than when we’re flat on our backs, and the researchers wondered whether these body positions were interacting with our motivations to change the brain’s response.

So Harmon-Jones and Peterson asked 46 participants to write a short essay before wiring them up to an EEG that measured the electrical activity across the brain.

The participants then put on headphones and listened as someone else read their essay and rated the author on personal characteristics, such as intelligence and competence. Some participants listened while lying down, others while in the sitting position.

What they didn’t know was that the ‘raters’ were actually pre-recorded audio, and while some heard a benign commentary on their work, other participants heard the other ‘person’ slagging-off them off and harshly rating the participant and their personality.

In line with the ‘ready to respond’ theory, when the participants were angry and sitting up, the left frontal lobe was much more active than the right – but when angry and lying down, there was no difference.

First off, the findings provide evidence that body position interacts with how the brain processes emotion, perhaps depending on which actions are immediately possible.

But more importantly, the experiment might also indicate that different neuroscience techniques may be throwing up varying results because of the differing body positions needed to take the tests.

Although this is only an initial study, it could be a major spanner in the works for cognitive science which often assumes that clumping together evidence from a whole range of techniques gives a better idea of what’s going on.

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