We came across more intelligence research by Jonathan Wai of the Duke University Talent Identification Program, who co-authored the paper on how SAT scores prove that we are getting smarter (though he told us that, as is mentioned in the study, they don't know if these are "real gains" or the result of other factors, like increased test-taking sophistication).

In another study, "Spatial Ability for STEM Domains: Aligning Over 50 Years of Cumulative Psychological Knowledge Solidifies Its Importance," Wai evaluated the general intelligence of people across professions. He and his co-researchers at Vanderbilt University looked at a random sample of 400,000 high schoolers (from ProjectTalent, which tracked them for 11 years), and the resulting chart shows verbal, spatial and math ability (labeled as V,S and M) as measured by a series of tests.