Effectiveness of Positive Hypothesis Testing for Cooperative Groups.

In a rule induction problem positive hypothesis tests select evidence that the tester expects to be an example of the correct rule if the hypothesis is correct, whereas negative hypothesis tests select evidence that the tester expects to be a nonexample if the hypothesis is correct. We extend previous analyses of the effectiveness of positive and negative tests for ambiguous verification or conclusive falsification of hypotheses by emphasizing the importance of examples following positive or negative tests. Cooperative four-person groups solved rule induction problems from a single known example of the correct rule by proposing hypotheses and selecting evidence on each of four arrays on a series of trials. There were more examples following positive tests than negative tests. The transition probability from an incorrect hypothesis on trial t to the correct hypothesis on trial t + 1 was higher for positive tests than for negative tests, higher for positive tests followed by examples than positive tests followed by nonexamples, and higher for negative tests followed by examples than negative tests followed by nonexamples. Once the group proposed the correct hypothesis on trial t they were highly likely to continue to propose the correct hypothesis on trial t + 1. Copyright 1998 Academic Press.