Adapting to Artificial Intelligence: Worker Skill Investment after ChatGPT
How do incumbent workers adjust their human capital when a new technology changes the value of existing skills? I study this question using quarterly résumé histories for 1.5 million U.S. workers from 2018 through 2025 and the public release of ChatGPT as a common shock. Treatment intensity is the pre-release AI exposure of a worker's occupation. Workers in more exposed occupations become substantially more likely to earn AI-related credentials after ChatGPT. This increase does not represent a broad expansion of training: the same workers reduce certification in adjacent technical fields, including data science and cloud/IT, and in other discretionary subjects such as marketing and finance, while safety and compliance credentials do not move and total certification does not increase. The response is therefore primarily a reallocation of human-capital investment across skills. Adjustment is stronger among postgraduates, workers with technical backgrounds, employees at large firms, workers with shorter tenure, and workers already employed in technology industries. Employer demand for AI skills subsequently rises more in exposed occupations, but worker certification begins to increase before this rise in vacancy demand becomes clearly detectable. The findings are consistent with workers reallocating skill investment in anticipation of technological change before changes in posted labor demand are fully visible.