Collective versus individual induction with single versus multiple hypotheses.

Four-person cooperative groups and 4 independent individuals solved rule induction problems by proposing 1, 2, or 4 hypotheses per trial while selecting the same amount of evidence per trial. Groups performed at the level of the best individuals and better than the 2nd-best, 3rd-best, and 4th-best individuals for both correct hypotheses and nonplausible hypotheses. Increasing the number of proposed hypotheses from 1 to 2 to 4 did not increase correct hypotheses but increased nonplausible hypotheses. Transition probabilities from hypotheses on trial t to t + 1 indicated superior performance for the groups and best individuals for each of positive and negative hypothesis tests followed by examples and nonexamples; once the groups and best individuals proposed the correct hypothesis, they were more likely to continue to propose it than the other individuals.