Co-actors a group of people working simultaneously and individually on a non-competitive task. The presence of others improves the speed with which people do simple multiplication problems and cross out designated letters. It also improves the accuracy with which people perform simple motor tasks. Social facilitation (1) original meaning: the tendency of people to perform simple or well-learned tasks better when others are present; (2) current meaning: the strengthening of dominant (prevalent, likely) responses owing to the presence of others. Some tasks the presence of others hinders performance. The presence of others diminishes efficiency at learning nonsense syllables, completing a maze, and performing complex multiplication problems. Arousal enhances whatever response tendency is dominant. If social arousal facilitates dominant responses, it should boost performance on easy tasks and hurt performance on difficult tasks. Social arousal facilitates dominant responses, whether right or wrong.