Tuning in to another person's action capabilities: Perceiving maximal jumping-reach height from walking kinematics.

Abstract

Three experiments investigated the ability to perceive the maximum height to which another actor could jump to reach an object. Experiment 1 determined the accuracy of estimates for another actor's maximal reach-with-jump height and compared these estimates to estimates of the actor's standing maximal reaching height and to estimates of the perceiver's own maximal reaching and reach-with-jump height. Perception of another actor's maximum reach-with-jump height was less accurate than the other estimates, but still accurate to within 8% error. The actor's reach-with-jump height was modified in Experiment 2 by attaching weights around the actor's ankles. Perceivers, who were explicitly aware of the manipulation, adjusted their maximum reach-with-jump estimates for the actor accordingly. In Experiment 3, perceivers were not explicitly aware of the weight manipulation, but provided significantly lower maximum reach-with-jump estimates after watching the actor walk while wearing the weights compared to estimates obtained after watching the actor walk while not wearing the weights. The results suggest that the actor's walking pattern was informative about the actor's capacity to produce a different action, jumping to reach an object.

Perceiving action boundaries: Learning effects in perceiving maximum jumping-reach affordances

“…Ramenzoni et al (2008) found that after watching an actor walk while the actor wore ankle weights that reduced his or her maximum jumping-reach height, observers who were not explicitly aware of the presence of the weights provided appropriately lower perceptual category boundaries (i.e., the boundary separating what could be reached by a vertical jump and what was out of reach) than they provided for the actor when he or she was unencumbered. The result indicates that observers are often quite sensitive to the action capabilities of others or at least to changes in action capabilities.…”

“…In previous studies, we found that although perceivers are fairly accurate at perceiving maximum jumping-reach height affordances for themselves and an actor, some degree of error-typically, underestimation on the order of 10-15 cm (e.g., Ramenzoni et al, 2008)-was observed. This indicates room for improvement that could be achieved through learning.…”

“…This indicates room for improvement that could be achieved through learning. In the present study, we used procedures similar to those of Ramenzoni et al (2008) to investigate processes of perceptual learning related to the perception of affordances for an actor. In Experiment 1, we determined whether estimates of the maximum height one could reach by jumping improved in accuracy over time (i.e., with repeated opportunities to sample the optic array and to provide perceptual reports).…”

“…The participants therefore did not see the other member of the pair perform the task until the experiment was over, although they did have opportunities to observe each other walking around the laboratory during the experiment before data collection occurred (cf. Ramenzoni et al, 2008). At the conclusion of the experimental trials, each participant performed the jumpingreach task.…”

“…Prior research has shown that perceivers can refine their estimates of another person's maximum jumping-reach height if they are able to observe the person performing a related but nonidentical action, such as walking, because that activity is informative about the actor's capabilities (Ramenzoni et al, 2008). Even without introducing new potential sources of information, providing a perceiver with repeated opportunities to sample the optic array might allow the perceiver to extract new information that may have previously gone undetected (Mark, Balliett, Craver, Douglas, & Fox, 1990).…”