There's a classic "problem" (meaning one that our brains have to solve, not us, though we do have to solve how our brains do it) in sensory perception: the cocktail party problem. When we're at a cocktail party (or, for those of us like me who are not swanky enough to go to cocktail parties, at a bar or a crowded coffee shop or a conference), and we are trying to focus on conversation with a single person while everyone else is also talking...how DO we do that? How can we pick out a single voice and understand it when other voices around us are as loud or louder as the one we are trying to hear? Well, some of it is attention, and it turns out that some of it may also be the face. Focus on the face. Head over to Neurotic Physiology and check it out.
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