Our research aims toward a method of evaluating how invasion of personal space by a robot, with appropriate context, affects human comfort. Work has been done to define comfortable social distances between humans and robots using the stop distance technique. But we aim toward filling an apparent gap in human-robot proxemics research: the results of physical interaction within that social distance. This paper describes our implementation of a testbed to evaluate how comfort changes as a result of invasion of personal space by a robot during a collaborative task with a shared workspace. The study we have designed and piloted causes the robot to reach into the human’s personal space at different distances and urgency levels. We have also identified some ways in which further exploration in this area can be done.