A symbolic interactionist would emphasize the ways in which people respond or interpret the actions of people, and how their responses reflected and influenced normalized gender roles. They could study interactions in the family, in the workplace, or anywhere else, and would focus on what behaviors people interpreted as male or female. The way people interpret these behaviors would obviously inform gender prejudice.
A functionalist might focus on the roles gender roles played in the overall functioning of the society, and how, in turn, people feared for the overall health of society as gender roles changed. Often these anxieties can lead to gender prejudice.
A conflict theorist would be interested in the connections between gender prejudice as a means for men to maintain power over women. They could argue that the need to maintain power was of psychological origins, or that it had to do with division of labor, a traditional Marxist feminist explanation.