What factors contribute to the presence of stereotyping?

Stereotyping is often the result of simple intellectual laziness. It is faster and easier to judge people on the basis of the group to which they belong, rather than getting to know them as individuals. In addition many people feel that the group to which they belong is in competition with other groups to which other people belong, and they therefore seek advantages for their own group at the expense of other groups. One of the ways of doing this is to attribute stereotypical attributes to members of other groups. If, for example, you claim that all Irish are drunks (and you personally are English) then you may enjoy feeling that your ethnic group is less prone to Alcoholism than some other ethnic group, and you may even use that as a reason to discriminate against supposedly drunk Irish people.