In today's excerpt--moods:
"One way moods differ from the grosser feelings of emotions, psychologists tell us, has to do with the ineffability of their causes: while we typically know what has caused an outright emotion, we often find ourselves in one or another mood without knowing its source. [Experiments] suggest, though, that our world may be filled with mood triggers that we fail to notice--everything from the saccharine Muzak in an elevator to the sour tone in someone's voice.
"For instance, take the expressions we see on other people's faces. As Swedish researchers found, merely seeing a picture of a happy face elicits fleeting activity in the muscles that pull the mouth into a smile. Indeed, whenever we gaze at a photograph of someone whose face displays a strong emotion, like sadness, disgust, or joy, our facial muscles automatically start to mirror the other's facial expression. ...
"We mimic the happiness of a smiling face, pulling our own muscles into a subtle grin, even though we may be unaware that we have seen the smile. That mimicked slight smile might not be obvious to the naked eye, but scientists monitoring facial muscles track such emotional mirroring clearly. It's as though our face were being preset, getting ready to display the full emotion. This mimicry has a bit of a biological consequence, since our facial expressions trigger within us the feelings we display. We can stir any emotion by intentionally setting our facial muscles for that feeling: just clench a pencil in your teeth, and you will force your face into a smile, which subtly evokes a positive feeling.
"Edgar Allan Poe had an intuitive grasp of this principle. He wrote: 'When I wish to find out how good or how wicked anyone is, or what his thoughts are at the moment, I fashion the expression of my face, as accurately as possible, in accordance with the expression of his, and then wait to see what thoughts or sentiments arise in my own mind or heart, as if to match or correspond with the expression.' "
Daniel Goleman, Social Intelligence, Bantam, 2006, 18-19.