The Effect of Intelligence on Job Performance is Intuitive
By Bryan Caplan
From Schmidt and Hunter, “General Mental Ability in the World of World” (2004, Journal of Personality and Social Psychology):
Why Is GMA [General Mental Ability] So Important for Job Performance?
It can be difficult for people to accept facts and findings they do not like if they see no reason why the findings should or could be true. When Alfred Weggner advanced the theory of plate tectonics early in the 20th century, geologists could think of no means by
which continents or continental plates could move around. Not knowing of any plausible mechanism or explanation for the movement of continents, they found Weggner’s theory implausible and rejected it. Many people have had the same reaction to the empirical
findings showing the GMA is highly predictive of job performance. The finding does not seem plausible to them because they cannot think of a reason why such a strong relationship should exist. In fact, their intuition may tell them that personality and other non-cognitive traits are more important than GMA (Hunter & Schmidt, 1996). However, as in the case of plate tectonics theory, there is an explanation. Causal analyses of the determinants of job performance show that the major effect of GMA is on the acquisition of job knowledge: People who are higher in GMA acquire more job knowledge and acquire it faster. The amount of job-related knowledge required on even less complex jobs is much greater than is generally realized. Higher levels of job knowledge lead to higher levels of job performance. Viewed negatively, not knowing what one should be doing–or even not knowing all that one should about what one should be doing–is detrimental to job performance. In addition, knowing what one should be doing and how to do it depends strongly on GMA.
P.S. Basic economics is intuitive, too.