heuristics can sometimes save our lives.

should have been irrelevant,it still affected the students' estimates.
This is an example of the anchoring effect,and it's often used in marketing and negotiations to raise the prices that people are willing to pay.So, if heuristics lead to all these wrong decisions,
why do we even have them?Well, because they can be quite effective.For most of human history,survival depended on making quick decisions with limited information.When there's no time to logically analyze all the possibilities,heuristics can sometimes save our lives.