Figure: six simple faces, one per basic emotion, drawn from the facial signs Ekman describes. Happiness: lip corners pulled up, cheeks raised. Sadness: inner corners of the eyebrows pulled up and together, lip corners down. Anger: brows lowered and drawn together, lips pressed. Fear: brows raised and drawn together, eyes wide, lips stretched back toward the ears. Surprise: brows raised, eyes wide, jaw dropped. Disgust: nose wrinkled, upper lip raised. Each face lists its universal trigger: enjoyment of pleasant experiences, loss, interference with what we want, threat of harm, something sudden and unexpected, and something offensive, poisonous or contaminating.
Figure: a simulation of Ekman's refractory period after someone insults you. The emotion starts within a fraction of a second. Then new information arrives: an apology at 5 seconds, an explanation at 30 seconds, a friend saying it was a joke at 5 minutes, and your own memory that the person is kind at 30 minutes. A slider sets the refractory period: 2 seconds, 1 minute, 10 minutes or 1 hour. Any information that arrives during the refractory period bounces off and the anger stays high; information after it gets through and the anger fades. With a 2-second refractory period all four messages get through; with 1 hour, none do.
Figure: a toy model of hunger against disgust. Hunger urge rises with hours since the last meal, as 100 × (1 − e^(−hours/24)): 34 after 10 hours, 71 after 30 hours, 95 after 72 hours. Four foods have a disgust level: plain bread 0, an unfamiliar food from another culture 40, food that touched something rotten 80, and food you find truly disgusting 110. You eat a food only when hunger is higher than its disgust. Bread is eaten at once, the unfamiliar food after about 12.3 hours, the contaminated food after about 38.6 hours, and the truly disgusting food never, because hunger in this model can never pass 100.
Figure: a stomach with churning waves (peristalsis) moving across it, based on Walter Cannon's 1915 X-ray observations of a cat. Pressing "Startle" stops the waves instantly and the stomach goes slack. They stay stopped until you press "Pet the cat"; then the cat purrs and the waves start again. Cannon watched one young cat's stomach for more than an hour while its only sign of excitement was a twitching tail, and saw no waves at all.
Figure: two panels. Left, disgust stops eating: people will not eat food they find disgusting, even if it is the only food available (Ekman, 2003). Right, fear and anger stop digesting: saliva, gastric juice and stomach movements stop whenever pain, fear or rage is present (Cannon, 1915). Each panel shows a hunger bar being outweighed by an emotion bar.
Figure: five quotes on a timeline, each checked against the original text. David Hume, 1739: "Reason is, and ought only to be the slave of the passions." Charles Darwin, 1872: "The term 'disgust,' in its simplest sense, means something offensive to the taste." William James, 1884: "we feel sorry because we cry, angry because we strike, afraid because we tremble." Walter Cannon, 1915: digestion stops "whenever pain, fear, rage, or other strong excitement is present." Paul Ekman, 2003: "Emotion triumphs over the hunger drive!"