Questions 19 to 22 are based on the recording you have just heard.

Recording Two

    （19）“Stereotype” may sound like a bad word, but there’s nothing bad about it. For one thing, stereotypes are often accurate. When you ask people about their concept of stereotypes, they get it pretty much right. （19）]Also, stereotypes are often positive, particularly of groups that we ourselves belong to. Some of the statistical generalizations may be positive as some groups have reputations for being smart, for being loyal, for being brave, for all sorts of things that are not all negative. And so there’s nothing inherently wrong about stereotypes. But there are problems with stereotypes. For one thing, （20）they’re reliable insofar as they’re based on unbiased samples. But a lot of the information we get about human groups is through biased sources like how they’re represented in the media. And if these sources don’t give you an accurate depiction your stereotype won’t be accurate. For example, many Jews have been troubled by Shakespeare’s depiction of Shylock. If the only Jew you know is Shakespeare’s Shylock, it’s going to be avery bad impression. So one problem with stereotypes is while we are good at drawing conclusions from them, often our information isn’t reliable. （21）A second problem is that stereotypes, regardless of whether or not they’re accurate, can have a negative effect on the people that they apply to. And this is what psychologist, Claude Steele, described a s stereotype threat. He ha a vivid example of this. Here’s how to make African-American do worse on a math test. You have the test and you put on the test that they have to identify their race. The very act of acknowledging that they are African-American when given a test ignites in them thoughts of their own stereotype, which is negative regarding academics and that makes them do worse. Want to know how to make a woman do worse on a math test? Same thing, get her to write down her sex. One recent study found a sort of clever twist on this. （22）When Asian-American women are given a test and they’re marked down their race, they do better than they would otherwise do. They’re reminded of a positive stereotype that boosts their morale. You ask them, on the other hand, to mark down their sex, they do worse because they are reminded of a negative stereotype. That’s an example of how stereotypes have a potentially damaging effect on people.

20. What leads to the bias of stereotypes?

解析：A。问题为：什么导致了对刻板印象的偏见？录音提到，一方面刻板印象是可靠的，因为它们是基于无偏样本的。但是我们得到的关于人类群体的很多信息都是通过有偏见的来源获得的，因此答案选A。