As explained in this video it is commonly assumed that logically incoherent decision-making is irrational and costly in that it can lead e.g. to a decrease in happiness or health. An example of this would be a patient reacting differently if doctors speak of a 90% success rate of surgery instead of a 10% failure rate for the same procedure. The purpose of the study presented here was to examine if there is proof in the existing literature that incoherent decision-making actually has negative consequences and is rightly seen as irrational. * GERD GIGERENZER is Director at the Max Planck Institute for Human Development and Director of the Harding Center for Risk Literacy, both in Berlin, Germany. This LT Publication is divided into the following chapters: 0:00 Question 2:13 Method 4:41 Findings 6:06 Relevance 10:29 Outlook