This study compared the responses of human participants studying motor interference and motor coordination when they were interacting with three different types of visual stimuli: a humanoid robot, a pendulum, and a virtual moving dot. Participants' responses indicated that participants' beliefs about the engagement of the robot affected the elicitation of the motor interference effects. Together with research supporting the importance of other elements of robot appearance and behavior, such as bottom-up effects and biological motion profile, we hypothesize that it may be the overall perception (in this study, by the term "overall perception," we mean the human observer's overall perception of the robot in terms of appearance, motion, and observer's beliefs) of a robot as a " social entity" instead of any individual appearance or motion feature that is critical to elicit the interference effect in human-humanoid interaction. Moreover, motor coordination responses indicated that the participants tended to synchronize with agents with better overall perception, which were generally in-line with the above hypothesis. Based on all the results from this experimental study, the authors suggest that a humanoid robot with good overall perception as a " social entity" may facilitate " engaging" interactions with a human.