People from many different racial and ethnic backgrounds live in large countries such as the United States. Because of cultural differences and various prejudices, it can be difficult for individuals from one background to interact with individuals from another background. Fortunately, a line of research, conducted by sociologists and social psychologists, suggests that interaction among individuals from different backgrounds can indeed help overcome tensions arising from their different cultures and any prejudices they may hold. This happens because such contact helps disconfirm stereotypes that people may hold of those from different backgrounds. This theory is called:__________.