Results from an explorative video-based study on the influence of a counterpart’s arm configuration changes on arm configuration changes of test persons during a hand trajectory following task are presented. Test persons are instructed to repeatedly imitate sinusoidal horizontal hand trajectories of a human projection with their hand, while keeping their arms in a particular joint configuration. During the hand trajectory progression, the arm configuration of the projected human changes between elbow down and elbow right configuration in various combinations in a counterbalance design. Qualitative and quantitative results show evidence for involuntary imitations of arm configurations by the test persons, which may be exploited for assessment of the perceived level of human-likeness of robots as well as for integration in robot intelligent action planning in order to avoid potentially arising adverse situations, e.g. in case of (near) singular joint configurations or collisions.