Figure 8.

Eyeheight-scaled information for gap width. A: Definition of variables for the horizon ratio (Equation 3). B: Raising a false floor reduces the declination angle (${\mathrm{\alpha }}^{*}$) and increases the specified gap width (Equation 4). C: Mean percentage of “impassable” judgments: smaller gaps are judged as passable when the floor is raised (from Warren & Whang, 1987, with permission).