Do People Pick Up Variables that Reflect Object Height Relative to Actor Height When Perceiving Others’ Maximum Vertical One Degree-of-Freedom Reach Heights?

Jones et al. (2023) investigated what variable(s) people pick up when perceiving others’ maximum vertical one degree-of-freedom reach heights. Their results suggest participants may have picked up variables that reflect object height relative to actors’ top of head heights when actors’ upper bodies were visible, and object height relative to actors’ leg lengths when only actors’ lower bodies were visible. Leg length is highly correlated with overall height. Accordingly, Jones et al. argued participants may have picked up variables that reflect object height relative to actor height in both cases. The present research evaluated Jones et al.’s explanation. In two experiments, participants viewed point-light displays depicting an actor and object. In Experiment 1, actors were depicted with short or tall necks and markers placed on their full or upper bodies. In Experiment 2, actors were depicted with short or tall legs and markers placed on their full or lower bodies. These manipulations changed object height in relation to actors’ top of head heights (Experiment 1) and object height in relation to actors’ leg lengths (Experiment 2) but did not change the actors’ maximum vertical one degree-of-freedom reach heights. Participants adjusted the object’s height to what they perceived to be the actor’s maximum vertical one degree-of-freedom reach height. In Experiment 1, judgments for the short-necked actors were lower than judgments for the tall-necked actors. In Experiment 2, judgments for the short-legged actors were lower than judgments for the tall-legged actors in the Lower Body condition, but not in the Full Body condition. These results support Jones et al.’s explanation. Further, they move us closer to identifying candidate variables that people pick up when perceiving actors’ maximum vertical one degree-of-freedom reach heights and enhance our understanding about how people perceive others’ affordances.