Biomedical subjects

William Epstein

Publications and source records attributed to William Epstein.

4 recordsLinked to original sources

PubMed2005

Tool use affects perceived distance, but only when you intend to use it.

Recent research demonstrates neurologic and behavioral differences in people's responses to the space that is within and beyond reach. The present studies demonstrated a perceptual difference as well. Reachability was manipulated by having participants reach with and without a tool. Across 2 conditions, in which participants either held a tool or not, targets were presented at the same distances. Perceived distances to targets within reach holding the tool were compressed compared with targets that were beyond reach without it. These results suggest that reachability serves as a metric for perception. The 3rd experiment found that reachability only influenced perceived distance when the perceiver intended to reach. These experiments suggest that the authors perceive the environment in terms of our intentions and abilities to act within it.

Attention↗

PubMed2005

Distances appear different on hills.

When walking effort is increased due to manipulations such as wearing heavy backpacks, people perceive hills to be steeper and distances to be farther (Bhalla & Proffitt, 1999; Proffitt, Stefanucci, Banton, & Epstein, 2003). On the basis of these findings, we expected people to overestimate distances on steep hills relative to the same distances on flat ground, because of the increased effort required to ascend or descend them. This hypothesis is in contrast to the belief that distances are specified solely by optical and oculomotor information related to the geometry of the environment. To test the hypothesis, we investigated distance estimation on hills and flat terrains in natural and virtual environments. We found that participants judged steep uphill and downhill distances to be farther than the same distances on flat terrain. These results are inconsistent with the idea that spatial layout is perceived solely in terms of geometry, lending partial support to an effort hypothesis.

Adult↗

PubMed2004

Perceiving distance: a role of effort and intent.

Perceiving egocentric distance is not only a function of the optical variables to which it relates, but also a function of people's current physiological potential to perform intended actions. In a set of experiments, we showed that, as the effort associated with walking increases, perceived distance increases if the perceiver intends to walk the extent, but not if the perceiver intends to throw. Conversely, as the effort associated with throwing increases, perceived distance increases if people intend to throw to the target, but not if they intend to walk. Perceiving distance combines the geometry of the world with our behavior goals and the potential of our body to achieve these goals.

Adult↗

PubMed2003

The role of effort in perceiving distance.

Berkeley proposed that space is perceived in terms of effort. Consistent with his proposal, the present studies show that perceived egocentric distance increases when people are encumbered by wearing a heavy backpack or have completed a visual-motor adaptation that reduces the anticipated optic flow coinciding with walking effort. In accord with Berkeley's proposal and Gibson's theory of affordances, these studies show that the perception of spatial layout is influenced by locomotor effort.

Adolescent↗