Psychology Investigated: The two-factor theory of emotion.

Background: The two-factor theory proposed that emotion is based on physiological arousal and cognitive labeling.

Aim: To investigate the role of physiological arousal and cognitive labeling in emotional experience.

Procedure: Participants were injected with epinephrine (adrenaline) or a placebo.

Participants were then exposed to either a euphoric or angry confederate.

Participants were asked to describe their feelings.

Sample: 184 male participants.

Sampling Technique: Opportunity sampling.

Experimental Design: Independent measures.

Controls: Participants who received a placebo were the control group.

Ethical Issues: The use of epinephrine (adrenaline) could have caused potential health risks. Participants were not informed about the true nature of the study, which raises concerns about informed consent.