Halo Effect

The psychologist Edward Thorndike named the effect about a century ago, after noticing that officers who rated a soldier highly on one quality tended to rate him highly on all the others. Kahneman explains it as System 1 keeping the story simple: a coherent picture, in which a likeable person is also competent and honest, is easier to hold than a mixed one, so the first trait we notice sets the tone for the rest. Order matters for the same reason. Solomon Asch showed that a person described as intelligent and industrious before stubborn and envious is judged more kindly than one described by the same words in reverse. Kahneman found the halo in his own work. Grading exam essays one student at a time, he noticed that a strong first essay made him generous with the second. He changed his method, grading every student's answer to one question before moving to the next and hiding the earlier scores. The general lesson is to make judgements independent. In a meeting, the first confident speaker can spread one halo across the room; written judgements collected before discussion keep each view its own.