This experiment examined users' abilities to judge whether an autonomous robot can accomplish a given task. It was predicted that 1) participants would differentiate the action-capabilities of short and tall robots, 2) participants would base their judgments on an action-relevant scalar, and 3) participants' judgments would be accurate. All three predictions were supported. This is important because it suggests that users may be able to accurately judge whether an autonomous robot can accomplish a given task without having previously observed that robot perform that task. The ability to do so will be very important as users increasingly ask their robots to perform tasks that the robots' designers may have never considered.