Unfortunately we didn't test this longitudinally, so can't answer. But I'd speculate that there would be critical periods!

Key takeaway: We find broad support for intergroup contact theory—contact is negatively associated with prejudice across groups with a wide array of distinct group properties.

Across 80 groups, we find that intergroup contact was consistently associated with lower prejudice.

Does a group’s properties (e.g., size, permeability, warmth) matter? No. (But we thought they would!)

Does the type of intergroup contact matter? No.

It is well-known that intergroup contact reduces prejudice.

However, existing research has largely tested the same type of groups but numerous other types of groups exist and they are not all the same (think: Asian people vs introverts vs people who live in the same neighbourhood).

And you can't use the cheap paint I think! When I was teaching in junior college years ago they used the cheap paint and the markers would stain the wall purple urgh