Pulling out all the stops to make the distance: Effects of effort and optical information in distance perception responses made by rope pulling

Human observers perceive distance in remarkably stable and consistent manner across response methods and experimental paradigms. Most empirical work on the problem focused exclusively on geometrical variables, such as angle of declination below the horizon (Ooi, Wu, & He, 2001 ), with more recent considerations of nonvisual factors, such as effort (Proffitt, 2006 ). Hajnal, Bunch, and Kelty-Stephen ( 2014 ) showed that in addition to the object’s physical angle of declination below the horizon, nonvisual variables related to effort were utilized when making distance estimates to objects placed on a sloped ramp. In that experiment, the horizontal ground surface was visible in the background when viewing objects placed on the sloped surface. To further investigate the joint utility of geometric and effort-based variables, we tested the effect of both classes of predictors on a natural hillside where a flat, horizontal surface was not visible in the background. This setup allowed us to evaluate whether observers rely on the same information to perceive distance on ramps versus real hills. The present research implicates the hypothesis that perceived effort and the geometry of space determine distance perception through interactions across multiple temporal scales of perceptual competence.