There is evidence that attentional control mechanisms in humans can be boosted in performance contexts involving the presence of other human agents, compared with isolation. This phenomenon was investigated here with the presence of artificial agents, that is, humanoid robots in the context of the well-known Stroop task requiring attentional control for successful performance. We expected and found beneficial effects of robotic presence (compared with isolation) on standard Stroop performance and response conflict resolution (a specific component of Stroop performance) exclusively when robotic presence triggered anthropomorphic inferences based on prior verbal interactions with the robot (a social robot condition contrasted with the presence of the same robot without any prior interactions). Participants’ anthropomorphic inferences about the social robot actually mediated its influence on attentional control, indicating the social nature of this influence. These findings provide further reasons to pay special attention to human-robot interactions and open new avenues of research in social robotics.