Allport’s four optimal conditions are facilitating rather than necessary for contact effects.

Evidence

In many ways, this stance reverses Allport’s approach. It starts with the prediction that intergroup contact will generally diminish prejudice, but the magnitude of this effect will depend on the presence or absence of a large array of facilitating factors – not just the four emphasized by Allport. In particular, this approach focuses special attention on those negative factors that can subvert contact’s typical reduction of prejudice. — , Rudman, Laurie A - On the Nature of…, 1712