Physiological arousal is the starting point for emotion

In the Schachter-Singer Two-Factor theory of emotion, the first factor in causing an emotion is physiological arousal. According to the two factor model, physiological responses are a necessary, though not sufficient, condition for emotions. The Schachter-Singer theory shares this contention in common with the earlier James-Lange theory of emotion, which argued that emotions are directly and solely the results of physiological responses. Unlike James-Lange, the Schachter-Singer theory describes physiological arousal as only the first step in forming emotions, which is followed by cognitive interpretation before an actual emotional response occurs.