Where and Why g Matters: Not a Mystery

The general mental ability factor--g--is the best single predictor of job performance. It is probably the best measured and most studied human trait in all of psychology. g is a highly general capability for processing complex information of any type. This explains its great value in predicting job performance. Theoretical obtuseness about g is too often used to justify so-called technical advances in personnel selection that minimize, for sociopolitical purposes, the use of g in hiring. One of the simplest facts about mental abilities provides one of the most important clues to the nature of g. The g factor shows up in nonpsychometric tests as well, providing more evidence for both its reality and generality. Understanding g as a construct is essential for understanding why and where g enhances performance of everyday tasks. The facade promotes the false belief that the impact of g is small, unpredictable, or ill-understood.