Your friend is a psychology major who tells you, “I was at a party last night. During the course of the evening, my general level of arousal increased. Since I was in a party where people were...

Your friend is a psychology major who tells you, “I was at a party last night. During the course of the evening, my general level of arousal increased. Since I was in a party where people were enjoying themselves, I assume I must have felt happy.” What theory of emotion does your friend subscribe to?