More Than General Intelligence: Cognitive Abilities and Class Structure

Intelligence is multidimensional—individuals differ in their level of general intelligence ( g ) and specific abilities. g is known to shape aspects of socioeconomic status (SES); however, little is known about how specific abilities shape SES. We evaluated the role of specific abilities in two large, representative samples: the National Longitudinal Studies of Youth 1979 and 1997. Using ten tests from the Armed Services Vocational Aptitude Battery, we identified general intelligence and orthogonal variation in three specific abilities, which we labeled tech, speed, and math-verbal. Performance on specific abilities in youth (14–22 years old) predicted later-life education, income, and occupational status. These associations held even between siblings. In contrast to the common claim that specific abilities add little more explanatory power to g , we concluded that specific abilities have 30–57% of the importance of g . We also examined how specific abilities shape occupations. The average ability profiles across occupations generally followed stereotypes. Metal workers, mechanics, and engineers scored high in tech ability, while religious workers and lawyers scored low. Engineers, doctors, and computer scientists had a high level of math-verbal ability. We estimated the degree of occupational clustering—the multiple correlation of occupations with a cognitive ability. While the strongest clustering was on g , there was also substantial clustering on specific abilities. The most influential specific ability for occupations was tech ability, especially in men, where clustering on tech ability was around 80% as large as the clustering on g .