Once heretical, behavioral economics is now mainstream. Money managers employ its insights about the limits of rationality in understanding investor behavior and exploiting stock-pricing anomalies. Policy makers use behavioral principles to boost participation in retirement-savings plans. Marketers now understand why some promotions entice consumers and others don’t.

Yet very few corporate strategists making important decisions consciously take into account the cognitive biases—systematic tendencies to deviate from rational calculations—revealed by behavioral economics. It’s easy to see why: unlike in fields such as finance and marketing, where executives can use psychology to make the most of the biases residing in others, in strategic decision making leaders need to recognize their own biases. So despite growing awareness of behavioral economics and numerous efforts by management writers, including ourselves, to make the case for its application, most executives have a justifiably difficult time knowing how to harness its power.¹

This is not to say that executives think their strategic decisions are perfect. In a recent McKinsey Quarterly survey of 2,207 executives, only 28 percent said that the quality of strategic decisions in their companies was generally good, 60 percent thought that bad decisions were about as frequent as good ones, and the remaining 12 percent thought good decisions were altogether infrequent.² Our candid conversations with senior executives behind closed doors reveal a similar unease with the quality of decision making and confirm the significant body of research indicating that cognitive biases affect the most important strategic decisions made by the smartest managers in the best companies. Mergers routinely fail to deliver the expected synergies.³ Strategic plans often ignore competitive responses.⁴ And large investment projects are over budget and over time—over and over again.⁵