There are many studies showing how quickly people notice and react to threatening facial expressions. This unconscious and rapid interpretation probably take place in the amygdala located inside the temples on either side of the head. These structures get information from the eyes directly via the thalamus, which means that the emotional interpretation begins within a hundredth of a second after something is registered by the eye. Higher systems in the frontal lobes get the visual information much later, around two-tenths of a second. By that time, the information has already been processed fairly thoroughly and can form the basis for a more balanced action, such as holding back an irrelevant emotional reaction. Recent studies indicate that the amygdala can react to both positive and negative emotional stimuli. This also includes learned, genetically programmed or expected reactions of fear.
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