From: The World In Your Head by Steven Lehar

Fig. 4.7 (A) A trapezoidal stimulus tends to be perceived as a rectangle viewed in perspective. (B) The perspective modified spatial representation whose dimensions are shrunken in height and breadth as a function of depth. (C) The projection of a field of influence into depth of the two-dimensional trapezoidal stimulus does not shrink with depth but is projected in parallel. (D) Several possible perceptual interpretations of the trapezoidal stimulus (darker gray), one of which (depicted in black outline) represents a regular rectangle viewed in perspective, because the convergence of its sides exactly matches the convergence of the space itself. (E) The distorted reference grid is projected onto the distorted surface to show how it is perceived to be both distorted, and at the same time perceived to be rectangular, exactly as observed in perception.