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Six Predictions about the Decision Making of Animal and Human Groups


Mathematics Department, Uppsala University, Sweden. E-mail:


We review and extend theoretical and empirical studies of how groups make decisions using combinations of private information and preference copying. We give six tested or testable predictions arising from models: (i) group decisions involve both true and false cascades; (ii) a small number of leaders can heavily influence a decision; (iii) individuals in groups make accurate and fast decisions; (iv) irrelevant alternatives change preferences; (v) optimal group size depends on the number of options; and (vi) pairs of higher quality options are more difficult to distinguish than lower quality options. We discuss our approach in the context of human organisations. Copyright © 2012 John Wiley & Sons, Ltd.