They might matter a lot because humans have, in general, a confirmation bias such that once you believe something other information is then encoded along the likes to support what you believe.

可能是因为人…,所有人都有确认偏向,也就是说，一旦你相信了某件事,其他信息都会被你解读成,支持你所相信的信息。

耶鲁公开课 - 心理学导论课程节选

If you believe black men are criminals, then when you see a black man who is a criminal you'll chalk it down as support but you'll pay less attention to evidence that white men are criminals and some black men are not criminals.

如果你相信黑人都是罪犯，当你看到一个是罪犯的黑人时,你就会觉得这是证据,但你不会注意其他证据,证明白人也有罪犯,黑人也有不是罪犯的。

耶鲁公开课 - 心理学导论课程节选