The first theory is the James-Lange Theory. The James-Lange theory is our experience of emotion is our awareness of our physiological responses to emotion arousing stimuli. For example if we see an oncoming car our first is arousal we are experiencing is pouding heart and then our emotion is fear.
The second theory is the Cannon-Bard Theory. This theory is our experience of emotion aroussing stimulus simultaneously triggers responses and emotions. For example if we see an oncoming car our pysiological response and experienced emotion are seperate but we are experiencing them both at the same time simultaneously.
The last theory is the Two-Factor Theory. This theory or also know as the Schachter Singer theory is that one must experience emotion one must be physically aroused and cognitively label the arousal. For example we see an oncoming car and experiencing the pysciological repsonse while labeling that "you're afraid" at the same time and then experiencing the emotion of fear immediately after.