Judging People From Too Little

Two builders come to quote for your loft. The first is on time, in a spotless van, with a firm handshake, and before he’s even climbed the ladder you’re picturing neat joinery. The second turns up 40 minutes late and is short with you, and you’ve quietly filed him as a cowboy.

That spreading is the halo effect: one impression, often a liked one, colours your judgement of other qualities you haven’t checked. Its negative twin, where one bad impression drags everything else down, is sometimes called the horn effect. Your mind works like a novelist: give it a single detail and it writes the whole character, consistent and convincing, from very little.