In a now classic study, Schachter and Singer gave injections to persons participating in an experiment they were told was for testing the effects of a vitamin compound on vision.⁴¹ In fact, half the participants received an injection of epinephrine (adrenaline), which reliably produces increased respiration and heart rate, slight muscle tremors, and an "edgy" feeling. The other participants received a placebo (saline solution), which produces no physiological feelings. Hence, the experimenters could be fairly assured that only the experimental group would experience physiological arousal. The participants in the experimental group were further divided into three groups: One group was told truthfully what physiological effects to anticipate; one group was misinformed and told to anticipate numbness, itching, and perhaps a headache; and one group was given no information. Contextual cues were then provided for all persons in the experiment. The cues were provided by "stooges" of the experimenter, who were in the room with the real subjects, presumably as participants in the experiment. The stooges acted either euphoric or angry.

Results of the experiment were generally as predicted and support a cognition-plus-arousal theory of emotional experience. Persons who experienced no physiological arousal (the placebo [saline solution] group), or who were given correct information as to expectations, did not use environmental cues to label their emotions. On the other hand, those with incorrect information or no information tended to interpret their emotions to be congruent with the cues -- as euphoric when the stooges acted euphoric, and as angry when the stooges acted angry. Both observation (through one-way mirrors) and self-report measures were used in this study. In both experimental groups, physiological arousal was generally properly identified (e.g., change in heart rate). The placebo group reported no physiological changes. Hence, Schachter and Singer argued that, given a situation of unanticipated physiological arousal, external cues (in this case, the 'stooges' feigned emotional behavior) influence the labeling of what emotion is occurring -- angry, happy, or sad, depending upon the context for unanticipated physiological arousal. Specific emotions are thus socially constructed.