Running head: PAUL MEEHL AND FAST AND FRUGAL HEURISTICS From Meehl (1954) to Fast and Frugal Heuristics (And Back): New Insights into How to Bridge the Clinical-Actuarial Divide

It is hard to overestimate Paul Meehl’s influence on the psychology of judgment and decision making. His “disturbing little book” Clinical versus Statistical Prediction: A Theoretical Analysis and a Review of the Evidence is known as attacking human judgment and calling for replacing clinicians by linear actuarial methods. More than forty years later, fast and frugal heuristics—proposed as models of human judgment—were formalized, tested, and found to be surprisingly accurate, often more that the linear models Meehl advocated. We ask three questions: Do the findings of the two programs contradict each other? More generally, how are the programs conceptually connected? Is there anything they can learn from each other? After showing that there need not be a contradiction, we show that both programs are concerned with developing (a) domain-specific models of judgment and (b) nonlinear process models that arise from the bounded nature of judgment. We then elaborate the differences between the programs and discuss how these differences can be viewed as mutually instructive: First, we show that the heuristic models can help bridge the clinical-actuarial divide, that is, they can help improve the accuracy and usability of actuarial methods, beyond Meehl’s suggestions. Conversely, we argue that Meehl’s insistence on improving judgment highlights the importance of examining the descriptiveness and acceptance of heuristics in the clinical domain.