and I asked you to give yourself a percentage rating relative to the rest of the class, then if everybody was accurate, or at least not systematically biased, the number should add up to 50%.

我要你相比于其他同学的表现，给自己一个百分数，如果大家都准确地评价自己，或者说大家都不偏心于自己，那么平均百分数应该是50%的。

耶鲁公开课 - 心理学导论课程节选