Dopaminergic drugs have been established as influential for a variety of cognitive processes, but their effects vary based on the individual and the tasks. The same drug and dosage could be administered to two separate individuals, and one could experience cognitive enhancement while the other experiences adverse effects, demonstrating paradoxical effects. This study explored the mechanism behind the differential outcomes with dopaminergic drugs by utilizing the D2 receptor agonist bromocriptine, accompanied by fMRI measurements, to observe the reactions of this drug on areas of participants’ brains associated with flexible updating (striatum) and the stable maintenance of representations (prefrontal cortex). Researchers focused on the reaction of bromocriptine for two different participant groups: high- and low-impulsivity individuals. Results from the study suggested that bromocriptine improved attentional switching in high- but not low-impulsive subjects. These findings reveal the importance of taking into account individual variations in personality traits when predicting drug efficacy. Additionally, they present a key link between dopamine function, impulsivity and fronto-striatal activity during component processes of working memory.