His interest in technology began at Florida State University, where, in the late 1960s, he obtained his degree in experimental psychology, conducting research in their computer-assisted instruction laboratory.
In 1975, O'Neil was recruited to join the Defense Advanced Research Projects Agency (DARPA), where he ran a program on computer-based learning, including PLATO IV (the state-of-the-art computer-assisted instruction system with "600 terminals online at the same time").
At USC, he has been active in the development of technology-based student assessment approaches involving public schools through a research relationship with UCLA/CRESST.
With his graduate students at USC, O'Neil conducts research on the development of both trait and state measures of effort, anxiety, self-efficacy, and metacognition.
His USC activities also involved multimedia strategic planning (e.g., distance learning) and assessment of faculty and organizational productivity, as well as evaluation of games.