Cognitive studies are revealing key aspects of how drug abusers monitor and respond to negative feedback differently from non-abusers, and in doing so are adding an important piece to the conceptual puzzle that must be solved to understand, treat, and prevent drug abuse. In this review, we bring together two quite different lines of research, one addressing the selection of gambles in a risky decision task, and the other focused on imaging neural systems related to the detection and processing of errors. We suggest that diminished behavioural control, which is a cardinal feature of drug abuse, may be linked to alterations in the psychological and neural mechanisms that detect error signals and which, in turn, lead to optimization of behavioural responses.