You judged them in five seconds and were wrong for five months. First impressions deserve a second look.

First impressions form on almost nothing: a face, a tone, one sentence at the wrong moment. Then they get expensive, because everything the person does afterwards gets filed to match. You stop collecting new evidence, and five months later you are still carrying a conclusion you reached before you knew anything. Nobody is at their most themselves in the first thirty seconds.

Think of someone you wrote off early and cannot remember a specific reason for. Give them one real conversation with the old verdict set aside. You will either learn something new or confirm the old read on better grounds.