In 1974, James Laird conducted two experiments on how changes in facial expression can trigger changes in emotion.[5] Participants were asked to contract or relax various facial muscles, causing them to smile or frown without awareness of the nature of their expressions. Participants reported feeling more angry when frowning and happier when smiling. They also reported that cartoons viewed while they were smiling were more humorous than cartoons viewed while they were frowning. Furthermore, participants scored higher on aggression during frown trials than during smile trials, and scored higher on elation, surgency, and social affection factors during smile trials than during frown ones.[5] Laird interpreted these results as "indicating that an individual's expressive behavior mediates the quality of his emotional experience."[5] In other words, a person's facial expression can act as a cause of an emotional state, rather than an effect. Instead of smiling because you feel happy, you can make yourself feel happy by smiling.