While individual differences and their influence on training and performance have been widely examined in fields such as industrial or educational psychology, they have not been a strong focus of human factors research. The present study aims to investigate the relationship between individual characteristics and complex task performance with special consideration of interaction effects. Fifty engineering students participated in a four-hour training session on a simulated process control task and a testing session one week later. Before the training session, the following individual characteristics were assessed: risk-taking behavior, general mental ability (GMA), and need for cognition (NFC). Interaction effects of risk-taking behavior and GMA, as well as of risk-taking behavior and NFC, on performance were found. Twenty to 30% of the variance in system control performance was accounted for by the individual characteristics and their interaction effects. Findings suggest that interaction effects should be systematically investigated in future research concerning individual differences in the context of human-system interaction.