When evaluating another person’s emotions – happy, sad, angry, afraid – humans take cues from facial expressions. Neurons in a part of the brain called the amygdala “fire” in response to the visual stimulation as information is processed by the retina, the amygdala and a network of interconnected brain structures. Some of these regions respond just to the actual features of the face, whereas others respond to how things appear to the viewer, but it is unknown where in the brain this difference arises.