That is exactly what should happen, but I suspect that in real life it doesn't, largely because of anchoring and adjustment.
Suppose I know the average intelligence of a member of Group A is 115, and the average intelligence of a member of Group B is 85. After meeting and having a long, involved conversation with a specific member of either group, I should probably toss out my knowledge of the average intelligence of their group and evaluate them based on the (much more pertinent) information I have gained from the conversation. But if I behave like most people do, I won't do that. Instead, I'll adjust my estimate from the original estimate supplied by the group average. Thus, my estimate of the intelligence of a particular individual from Group A will still be very different than my estimate of the intelligence of a particular individual from Group B with the same actual intelligence even after I have had a conversation (or two, or three) with both of them. How many conversations does it take for my estimates to converge? Do my estimates ever converge?
After meeting and having a long, involved conversation with a specific member of either group, I should probably toss out my knowledge of the average intelligence of their group and evaluate them based on the (much more pertinent) information I have gained from the conversation.
If your goal is to accurately judge intelligence this may not be a good approach. Universities moved away from basing admissions decisions primarily on interviews and towards emphasizing test scores and grades because 'long, involved conversation' tends to result in more unconsci...
A few examples (in approximately increasing order of controversy):
If you proceed anyway...