Perceiving geographical slant

Abstract

People judged the inclination of hills viewed either out-of-doors or in a computer-simulated virtual environment. Anglejudgments were obtained by having people (1) provide verbal estimates, (2) adjust a representation of the hill's cross-section, and (3) adjust a tilt board with their unseen hand. Geographical slant was greatly overestimated according to the first two measures, but not the third. Apparent slant judgments conformed to ratio scales, thereby enhancing sensitivity to the small inclines that must actually be traversed in everyday experience. It is proposed that the perceived exaggeration of geographical slant preserves the relationship between distal inclination and people's behavioral potential. Hills are harder to traverse as people become tired; hence, apparent slant increased with fatigue. Visuallyguided actions must be accommodated to the actual distal properties of the environment; consequently, the tilt board adjustments did not reflect apparent slant overestimations, nor were they influenced by fatigue. Consistent with the fact that steep hills are more difficult to descend than to ascend, these hills appeared steeper when viewed from the top.By east coast standards, Virginia is a mountainous state, and many of its roads appear quite steep, especially to midwestern visitors. Yet by law, roads in the state can be inclined no more than 9°from the horizontal, and 9°is a much smaller angle than the inclination that most people estimate these steep roads to have. This is an example ofa pervasive phenomenon: Hills appear to be steeper than they actually are. The first purpose of this paper is to provide a normative description of this overestimation in geographical slant perception.As we will show, a 5°hill is typically judged to be almost 20°in slant; however, when walking up a 5°hill, we do not raise our feet to accommodate a 20°incline and thereby stumble as we begin the ascent. The visual guidance oflocomotion shows no evidence of slant misperception. The second purpose of this paper is to show that a motoric index of geographical slant shows little evidence of the overestimations manifest in visual awareness. The paper's third purpose may be introduced with an anecdote.Not long ago, I (Proffitt) was riding in a l-day, 100-mile, bicycle tour, with the finish-line only a couple of miles ahead. The tour had traversed a number ofsmall mountains in a circuit that began and ended at a site in the rolling hills of the Virginia piedmont. The final hill before the finish seemed incredibly steep, and as I passed another rider I commented on how organizers of these affairs always seemed to arrange for the steepest hills to be located just before the finish. The other rider muttered an oath as she bemoaned what a cruel joke it was to make us climb this hill so late in the ride. (It would have been an even crueler joke to have informed her that the incline of this hill was only about r.) Now the hill in question was relatively steep, but it was far less so than many that we had previously encountered durin...

Visual–motor recalibration in geographical slant perception.

“…Be that as it may, people are not especially prone to stumble whenever the terrain over which they walk changes in slant. When ascending a 5° hill, people appropriately raise their feet to accommodate this incline, not a 20° one.In this and our previous article (Proffitt et al, 1995), we suggest that the exaggeration of slant in conscious awareness promotes the function of relating distal inclines to one's physiological potential. Given gravity and one's physiology, a long 5° hill is actually rather difficult to ascend, and consequently it appears to be quite steep.…”

“…In this and our previous article (Proffitt et al, 1995), we suggest that the exaggeration of slant in conscious awareness promotes the function of relating distal inclines to one's physiological potential. Given gravity and one's physiology, a long 5° hill is actually rather difficult to ascend, and consequently it appears to be quite steep.…”

“…For example, 5° hills appear to be about 20°, and 10° ones look to be about 30° (Proffitt, Bhalla, Gossweiler, & Midgett, 1995). Be that as it may, people are not especially prone to stumble whenever the terrain over which they walk changes in slant.…”

Does Energy Expenditure Affect the Perception of Egocentric Distance? A Failure to Replicate Experiment 1 of Proffitt, Stefanucci, Banton, and Epstein (2003)

“…In a series of recent papers, Proffitt and his colleagues have provided evidence that the visually perceived distance to a target is influenced both by the energy expenditure required to carry out an action spanning that distance and by the physiological state of the person (Bhalla & Proffitt, 1999;Proffitt, Bhalla, Gossweiler, & Midgett, 1995;Profitt, Stefanucci, Banton, & Epstein, 2003;Witt, Proffitt, & Epstein, 2004). In particular, Profitt et al (2003) reported that observers, who wore a heavy backpack while judging the distance to a target with the expectation of having to walk to it while wearing the backpack, reported greater distances than participants who did not wear backpacks.…”

A Final Reply to Hutchison and Loomis

“…After all, the most common action directed at the ground is, by far, walking. We have repeatedly found that manipulations of walking effort influence the perceived layout of the ground even if people do not actually walk the relevant extent (Bhalla, & Proffitt, 1999;Proffitt, Bhalla, Gossweiler, & Midgett, 1995;Proffitt, Stefanucci, Banton, & Epstein, 2003;Stefanucci, Proffitt, Banton, & Epstein, 2005). We have, of course, also found that effort for walking influences apparent distance when people do anticipate walking to targets (Witt, Proffitt, & Epstein, 2004).…”