Figure 1.

The slant hypothesis. A texture boundary is created when two different texture surfaces (depicted in side view as black and gray lines) abut on a flat ground surface. According to the SSIP hypothesis, the far texture surface will not be represented as coplanar with the near texture surface. Instead, the far texture surface will be subjected to the influence of the visual system's intrinsic bias. This leads the far texture surface to be represented with a slant error, η; hence, its upward slant representation (gray dash line). Accordingly, d’₁=d₁ and d’₂=d₂*sin(α)/sin(α+η), in which the latter is derived from the trigonometric relationship, d’₂/sin(α)=d₂/sin(180-α-η). Thus, the perceived egocentric distance of a target on the far texture surface (d=d’₁+d’₂) is less than the actual physical distance (d₁+d₂).