Illusion of Validity

The illusion of validity is the unwarranted confidence a person feels in the accuracy of their own judgments or predictions, particularly judgments based on a coherent-seeming pattern of information, even when the actual predictive accuracy of those judgments is known or demonstrable to be poor. The psychologist Daniel Kahneman, together with Amos Tversky, described and named the effect in the 1970s, drawing partly on Kahneman's own earlier experience as a military interviewer whose confident personality-based predictions about officer candidates' future performance proved to have little actual predictive validity despite feeling highly reliable at the time the judgments were made. The effect is discussed as an important limitation on expert judgment across fields such as clinical psychology, forecasting and personnel selection, since the subjective feeling of confidence in a judgment has repeatedly been shown to be a poor indicator of that judgment's actual accuracy.