Harmonizing Task Intensities Across Time

A growing literature has used the intensity of the tasks that workers perform to explain labor market outcomes. Despite significant changes in the workplace, this "task approach" is based on the questionable assumption that the intensity of tasks remains constant over time. I harmonize and compare the intensity of four broad task classes that workers perform -non-routine cognitive, non-routine manual, interpersonal, and routine- from 1980 to 2014 in the Dictionary of Occupation Title (DOT) and the Occupational Information Network (O*NET). I find the new fact that a sizable part of wage changes is due to increases in the return and the intensity of cognitive tasks. I show that my new fact has important implications for three well-documented wage trends during the last decades. First, it caused wage polarization because the intensities of cognitive tasks increased in both high-wage and low-wage occupations. Second, it increased the college premium because college graduates tend to work in occupations that are relatively intensive in cognitive tasks. Third, it reduced the gender-wage gap because women again tend to work in occupations that are relatively intensive in cognitive tasks. JEL Codes: E24, J24, J31.