Fig. 13. Schematic illustrations of the ambiguity of the slope of electric images at different body regions. (A) A cube opposite a flat sensory surface. The distance between the object and the sensory surface is constant. The resulting electric image is bell-shaped and the slope is steep (depicted by the red line intersecting the horizontal line to indicate the angles). (B) A spherical object opposite a flat sensory surface. The edges of the object are farther away than the middle of the object. Therefore the slope of the electric image is less steep. (C) A cube opposite a curved sensory surface. The edges of the object are farther away than the middle of the object. Compared to the trunk the slope is less. (D) A spherical object facing a curved sensory surface. As the distance between the edges of the object and the sensory surface is greater than for the flat surface (B) the slope is steeper.