Thursday, February 10, 2011

Men fear other men most - Gender specific brain activations in perceiving threat from dynamic faces and bodies

Wow, that title is a mouthful. Mariska Esther Kret, Swann Pichon, Julie Grèzes, and Beatrice de Gelder did an fMRI study of male and female brains (14 of each) - and the people who come with them - in response to either neutral and angry expressions (half) or neutral and fearful expressions (the other half) on either male or females subjects.

Men fear other men most

Partial results:

The amygdala showed more activity for faces than bodies as was shown by a main effect. However, an interaction between category and observer revealed that this increased activity for faces was specific to male observers. Although there was no interaction with gender of the actor, the enhanced response in the male observers for facial expressions, was only valid in case of female faces. The amygdala was not more responsive to emotional than neutral stimuli but showed enhanced activity for faces, in particular in the male observers, especially when they observed female faces.
It's worth reading the whole study, even though I take all fMRI stuff - even when seemingly definitive - as loosely held until I see replication or other support.

The upside of this research is that it shows a proclivity (either trained or evolutionary) for men to be more aware of and respondent to faces than are women. However, it is only statistically significant for neutral female faces - not angry female or either neutral or angry male faces - might be part of our "looking for loving" wiring. But this is only partial . . . mostly in the amygdala . . . there's more.

Whereas male observers responded more to threatening body expressions than females did, the opposite tendency was observed in the EBA (Extrastriate body area) for female observers. Females were not more responsive to faces than males, but the difference in brain activity following a threatening versus neutral face was significant in this region in female observers only. However, this difference score between threatening minus neutral faces was not significantly larger in female than in male observers. So, the three-way interaction between category, emotion, and observer in EBA was mainly driven by male observers’ response to threatening body expressions. Ishizu et al. (2009) found that males showed a greater response in EBA than females when imagining hand movement. Our male subjects possibly imagined themselves reacting to the threatening male actor more than females did. Alternatively, there was an automatic, increased response to threatening body expressions (Tamietto and de Gelder, 2010). This latter explanation is plausible because the male observers additionally showed a clear motor preparation response in the PM (Premotor cortex) and the pre-SMA (Pre-supplementary motor area) toward threatening male body expressions.

Our results are similar to previous studies that show male observers to be more reactive to threatening signals than female observers (Aleman and Swart, 2008; Fine et al., 2009). Hess et al. (2004) finds that facial cues linked to perceived dominance (square jaw, heavy eyebrows, high forehead) are more typical for men, who are generally perceived as more dominant than women. So far, nothing is known about bodily cues and perceived dominance in humans but the physical differences between men and women may be important for interpreting our results. If there is a significant difference in power or status between men and women, then threat from an anger expression can elicit different responses depending on the status or power of the angry person.

Interesting stuff. Emotional responses or emotion perception, the authors conclude, are dependent on whether the observed is a face or a body, and whether the observed and observers are male or female.

Full reference and link:
Kret, ME, Pichon, S, Grèzes, J & de Gelder, B. (2011). Men fear other men most - Gender specific brain activations in perceiving threat from dynamic faces and bodies - An fMRI study. Frontiers in Emotion Science, Vol. 2. DOI=10.3389/fpsyg.2011.00003

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