Kinematics Affect People’s Judgments of a Wheeled Robot’s Ability to Climb a Stair

The effect of wheel height and weight on people’s affordance judgements of a wheeled robot climbing a step was assessed in two experiments. Users must be able to understand their personal service robots’ abilities to perform tasks, such as climbing steps. Robots’ action capabilities can be considered using the theory of affordances. Affordances are the action-relevant relationships between attributes of an actor and attributes of its environment. There is ample evidence that people are sensitive to other people’s affordances. However, only limited research has been conducted to determine whether this generalizes to non-human actors, such as robots. We conducted two experiments which assessed whether people’s affordance judgements of a wheeled robot climing a step are affected by changes in the relationship between step height and robot wheel radius (Experiment 1) as well as weight (Experiment 2). Participants watched brief videos of different robots approaching steps. The participants indicated whether the robot could or could not climb the step. Participants correctly judged that robots which have larger wheel radiuses or are lighter would be able to climb taller steps compared to robots that have smaller wheel radiuses or are heavier. However, participants’ judgments were significantly different from the robots’ actual climbing abilities. This research provided evidence that participants can be sensitive to affordances for non-human actors and might use kinematics when perceiving them. The results indicate that robot users may benefit from viewing a robot’s appearance and movements when judging a robot’s affordances.