  Most people, including scientists, are subject to “confirmation bias” in that they look for data that are consistent with what they think might be true. Thus if they think the statement in the test is true, they might turn over the “2” card, since doing so cannot help but be consistent with the truth of the statement. What people tend not to search for is something that could disconfirm their hypothesis, such as finding out whether there is a vowel on the other side of card “7”. The groups that did well on this test turned over only cards “E” and “7”, since these are the only cards that could disconfirm the truth of the statement at issue. Mercier and Sperber suggest that the psychological dynamics of reasoning in groups guard against confirmation bias. Each member of a group can have an idea how to solve the problem at issue and put it to the group, but others in the group will tend to look critically at a proposal from someone else to see if the proposal has a flaw. There is in this way a division of cognitive labor within the group. While each member may suffer confirmation bias, as well as other biases, the whole group need not, since each member will try to disconfirm solutions offered by others. The upshot is that the group as a whole will tend to do well, unless everyone is biased in exactly the same way. The best groups comprise people who are cognitively diverse but listen well to each other.