How we change what others think, feel, believe and do
We tend to classify people who are not in our in-group as being similar to one another. ‘They’re all like that’ is a common reference term. In contrast, we see people in out in-group as being more individual.
We thus tend to use a set of stereotypes for people from different countries, cities and companies. These generalizations lead us to discriminate uniformly towards people from these groups.
When visiting a new country or group, the behavior of the first few people we meet will quickly be used to create a stereotype of the others in the same group.
Students shown videos of other students making a choice about music were asked to assess whether other students from the same college would make the same or different choices. When they were told the other students were from their college, they forecast that the other students would make a wide range of choices. When they were told that the other students were from another college, they forecast that other students from that college would choose very similar music.
Much of the fighting around the world is based on differences of religion. Zealots cast the other side as jointly and severally guilty for the sins of their peers and equally likely to commit the same acts of war. Thus genocide seems the only answer as they blindly fight on.
To form your own group, visibly cast selected other people as all having specific undesirable attributes. Act in a hostile manner to these out-group people when people you want to be in your group are around.
When dealing with a person, find their out-group biases and them deliberately show how you do not fall into any of those groups. Faced with overwhelming disconfirming evidence, they will be likely to accept you into their group.