High frequency of facial expressions corresponding to confusion, concentration, and worry in an analysis of naturally occurring facial expressions of Americans.

College students were instructed to observe symmetric and asymmetric facial expressions and to report the target's judgment of the "emotion" she or he was expressing, the facial movements involved, and the more expressive side. For both asymmetric and symmetric expressions, some of the most common emotions or states reported are neither included in standard taxonomies of emotion nor studied as important signals. Confusion is the most common descriptor reported for asymmetric expressions and is commonly reported for symmetrical expressions as well. Other frequent descriptors were think-concentrate and worry. Confusion is characterized principally by facial movements around the eyes and has many properties usually attributed to emotions. There was no evidence for lateralization of positive versus negative valenced states.