Other ; This is the author accepted manuscript. The final version is available from AAAS via http://dx.doi.org/10.1126/science.aaf3700 ; Abstract ; Cocaine addiction is a major public health problem that is particularly difficult to treat. Without medically proven pharmacological treatments, interventions to change the maladaptive behavior of addicted individuals mainly rely on psychosocial approaches. Here we report on impairments in cocaine-addicted patients to act purposefully toward a given goal and on the influence of extended training on their behavior. When patients were rewarded for their behavior, prolonged training improved their response rate toward the goal but simultaneously rendered them insensitive to the consequences of their actions. By contrast, overtraining of avoidance behavior had no effect on patient performance. Our findings illustrate the ineffectiveness of punitive approaches and highlight the potential for interventions that focus on improving goal-directed behavior and implementing more desirable habits to replace habitual drug-taking. ; Other ; Sir Henry Wellcome Postdoctoral Fellowship (Grant ID: 101521/Z/12/Z) ; Other ; Medical Research Council (Grant ID: MR/J012084/1) ; Other ; Wellcome Trust ; Other ; National Institute for Health Research