When does explicit justification impair decision making?

The idea that careful analysis leads to better decisions is pervasive in re search on decision making. Intriguingly, results raise the possibility that thinking about reasons for decisions before deciding may degrade decision quality. This paper reports the results of a laboratory study which examine d whether task characteristics critically influence the effects of thinking about reasons on decision quality. We found that explicit reasoning degrad ed judgement quality, objectively measured, on an 'intuitive' task. However , we also found that explicit reasoning enhanced performance on an 'analyti c' task. Copyright (C) 2000 John Wiley & Sons, Ltd.