Visual–motor recalibration in geographical slant perception.

In 4 experiments, it was shown that hills appear steeper to people who are encumbered by wearing a heavy backpack (Experiment 1), are fatigued (Experiment 2), are of low physical fitness (Experiment 3), or are elderly and/or in declining health (Experiment 4).Visually guided actions are unaffected by these manipulations of physiological potential.Although dissociable, the awareness and action systems were also shown to be interconnected.Recalibration of the transformation relating awareness and actions was found to occur over long-term changes in physiological potential (fitness level, age, and health) but not with transitory changes (fatigue and load).Findings are discussed in terms of a time-dependent coordination between the separate systems that control explicit visual awareness and visually guided action.In conscious awareness, the apparent slant of hills is greatly exaggerated.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.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.Given this proposal, we predict that geographical slant will change with changes in physiological potential.The first purpose of this article is to provide support for this prediction.In four experiments, we show that hills appear steeper when people are (a) encumbered by wearing a heavy backpack, (b) fatigued after a long run, (c) of low physical fitness, and (d) elderly or in poor health.