Even when people perform tasks poorly, they often report unrealistically positive estimates of their own abilities in these situations. To better understand the origins of such overconfidence, we investigated whether it could be predicted by individual differences in working memory, attentional control, and self-reported trait impulsivity. Overconfidence was estimated by contrasting objective and subjective measures of situation awareness (the ability to perceive and understand task-relevant information in the environment), acquired during a challenging air traffic control simulation. We found no significant relationships between overconfidence and either working memory or attentional control. However, increased impulsivity significantly predicted greater overconfidence. In addition, overall levels of overconfidence were lower in our complex task than in previous studies that used less-complex lab-based tasks. Our results suggest that overconfidence may not be linked to high-level cognitive abilities, but that dynamic tasks with frequent opportunities for performance feedback may reduce misconceptions about personal performance.