Despite a longstanding expert consensus about the importance of cognitive ability for life outcomes, contrary views continue to proliferate in scholarly & popular literature; we find no threshold beyond which greater IQ cease to be beneficial

Brown, Matt, Jonathan Wai, and Christopher Chabris. 2020. “Can You Ever Be Too Smart for Your Own Good? Linear and Nonlinear Effects of Cognitive Ability.” PsyArXiv. January 30. https://psyarxiv.com/rpgea/

Abstract: Despite a longstanding expert consensus about the importance of cognitive ability for life outcomes, contrary views continue to proliferate in scholarly and popular literature. This divergence of beliefs among researchers, practitioners, and the general public presents an obstacle for evidence-based policy and decision-making in a variety of settings. One commonly held idea is that greater cognitive ability does not matter or is actually harmful beyond a certain point (sometimes stated as either 100 or 120 IQ points). We empirically test these notions using data from four longitudinal, representative cohort studies comprising a total of 48,558 participants in the U.S. and U.K. from 1957 to the present. We find that cognitive ability measured in youth has a positive association with most occupational, educational, health, and social outcomes later in life. Most effects were characterized by a moderate-to-strong linear trend or a practically null effect (mean R2 = .002 to .256). Although we detected several nonlinear effects, they were small in magnitude (mean incremental R2= .001). We found no support for any detrimental effects of cognitive ability and no evidence for a threshold beyond which greater scores cease to be beneficial. Thus, greater cognitive ability is generally advantageous—and virtually never detrimental.