Variables affecting perceptual boundaries in bipedal stair climbing.

The present study examined the effects of hip joint mobility and relative leg strength on perceived and attained action boundaries in bipedal stair climbing. If action boundaries are directly perceived and action is intimately linked to perception, one should be able to quantify these boundaries (Warren, 1984) and identify what variables affect these perceived boundaries. In the present experiment the perceived and attained absolute and relative (riser height divided by leg length) action boundaries were significantly affected by hip joint flexibility. Relative leg strength also affected absolute and relative perceived action boundaries. These results clearly show that factors in addition to body size and body proportions may affect the perception of affordances and their boundaries.