Investigating What Variables People Pick Up When Perceiving Other People’s Maximum Vertical One Degree-of-Freedom Reach Heights to Inform the Design of Assistive Robots

Abstract We aim to design assistive robots that perceive people’s affordances in ways that are similar to how people perceive other people’s affordances. Toward that end, two experiments investigated what variables people pick up when perceiving actors’ maximum vertical one degree-of-freedom reach heights. In Experiment 1, point-light displays depicted actors who moved, were either tall or short, and had markers placed on either their whole body (head, shoulders, elbows, wrists, hands, hips, knees, & ankles), upper body (head, shoulders, elbows, wrists, & hands), lower body (hips, knees, & ankles), or ankles. Participants instructed the experimenter to adjust an object’s height so that it was just reachable. Experiment 2 was identical except actors moved or were still. In both experiments, judgment error for the Full Body condition was not significantly different from that for the Upper or Lower Body conditions, but was significantly different from that for the Ankles condition. In Experiment 2, that result replicated when actors moved and when they were still. These results suggest participants may have picked up object height in relation to actor height. Implications about how people perceive other people’s maximum vertical one degree-of-freedom reach heights and how that might inform assistive robot design are discussed.