The two factory of emotion states that after encountering an emotion provoking event one experiences a state of alertness also referred to as arousal. The second part of this theory states that one seeks to explain this arousal and therefore we label the arousal with an emotion. Emotions are therefore explanations we attach to arousal. This is an important concept because it explains how one's emotions can be interpreted, which enables us to better understand our actions and those of others.
Dutton and Aron did an experiment that supports this. An attractive female approached young men to take her survey and then went on to give them her phone number if they had any questions. This experiment was done on a sturdy bridge and then was repeated on a swaying bridge, 30% of the males called her back from the sturdy bridge and 60% of the males called her back that she approached on a swaying bridge. The swaying bridge caused the males to be aroused and therefore they were more attracted to the female that conducted the survey, which supports the two-factory theory of emotion.
Although this experiment supports this theory, other research supports that arousal intensifies emotions and can occur in the absence of arousal. The problem of replicability is shown through the research that arousal is not necessary for all emotional experience.