The Undoing Project: A Friendship That Changed Our Minds

When studying the nature of human decision making, Danny and Amos needed to understand how humans understand and perceive reality. If, for instance, someone receives an unfavorable medical diagnosis and must decide which treatment to select for their recovery, their understanding of reality would inform their decision. Even more important was the idea that people might have to modify their preconceived notions of reality to accept what was actually true. When Donald Redelmeier worked with Amos to understand decision making within a medical context, they found that a large group of arthritis patients insisted on the connection between their pain and their surrounding weather conditions, even when only a “few random moments […] justified their belief” (231).

All throughout Danny and Amos’s experiments, human decision making relied on what they called a “model” in one’s mind, in which every decision needed to be filtered through before the decision was made. As Lewis writes, “Danny and Amos had their first big general idea—the mind had these mechanisms for making judgments and decisions that were usually useful but also capable of generating serious error” (188). Therefore, if the mind could lead itself to make serious mistakes, its subsequent decision making might represent a disconnect from reality.