Remember that one time your girlfriend or boyfriend got ketchup on their nose while eating French fries and you thought it was hilarious, but immediately afterwards you felt guilty because they glared at you and growled for a napkin?
There is a word for that: ambivalence. The word ambivalence means that you feel two contradictory emotions (hilarity and guilty) simultaneously. Look a little more closely at the word ambivalence and you can probably guess what electrons and emotions have in common: valences. Emotional valences, like valence electrons, are shown outwardly on a persons face and they either attract (positive valence) or repel (negative valence) the person at which they are directed.
Many studies, since the advent of the fMRI, have examined the underlying circuitry involved in the expression and perception of emotion, especially negative valence emotions such as anger, sadness, and fear. The paper I analyzed is no exception to this rule: researchers from Kings College London, University College London, and the University of Z├╝rich worked together to a) ascertain the circuitry that underlies the processing of emotionally negative facial expressions, and b) determine whether or not the amygdala is involved in the conscious processing of emotive faces. Basically, they wanted to know if our first response to facial expressions is to think or react.
In the study, a pool of 40 subjects (selected based on a range of nonspecific qualities) were shown a set of 60 faces and a corresponding number of fixation crosses (an image of a white screen on which a + is superimposed), while in an fMRI. Each of the 60 faces displayed either a neutral expression or a negative expression (anger, fear, or sadness) and the subjects used a clicker to indicate whether the face did or did not show an emotion. For each face, the response time and accuracy was recorded and was used in concert with the data provided by the fMRI images. In addition to the tests performed using the fMRI, a battery of statistical tests corrected for noise and anatomical dissimilarities among participants.
The findings are significant: the amygdala is not the only cranial structure that modulates facial processing. To be more specific, their results show that while the amygdala is involved in the processing of facial affect(Dima et al 1) there are also pathways to and from the fusiform gyrus, the inferior occipital gyrus, and the ventrolateral prefrontal cortex, which do not involve the amygdala. Most notably, anger was mediated by the inferior occipital gyrus and ventrolateral prefrontal cortex, not the amygdala.
What does all of that mean?
Basically, our brains have evolved for cognition for so long that we now respond to physical or emotional danger (anger in this case) in a cognitive fashion. We think before we react to a potentially harmful event.
Now think back for a second to your girlfriend or boyfriend with ketchup all over their nose. If this research holds, you will not immediately react and give them the napkin; you will, in fact, think about the potential harm that could come to you if you do not (minimal: they probably will not punch you), and the potential benefits you will reap if you do not (photographic evidence of the event). As far as I am concerned this decision is easy: memory is leaky; emotions are transient; but a picture lasts a lifetime.
What would you do?