The hypothesis that perspective foreshortening leads to errors in the visual perception of angles, was tested in four experiments. An oblique to a z-dimension line was presented (a) on the ground in Experiments 1 and 2, and (b) on a wall in Experiments 3 and 4. Observers judged the acute angle between the oblique and the z-line. Foreshortening increased with the oblique’s distance along the z-line and, in Experiments 2 and 4, shorter distances from the eye to the ground or wall. As distance and eye-height vary, so does the target’s slant to the line of sight. We argue the apparent angles between the lines increased with foreshortening because vision underestimates the fast rate of foreshortening with elevation compared with the slower rates in azimuth.

在四个实验中检验了透视透视缩短会导致角度的视觉感知错误的假设。z尺寸线的斜角（a）在实验1和2中呈现在地面上，（b）在实验3和4中在墙壁上呈现。观察者判断斜角和z线之间的锐角。沿z线的倾斜距离会缩短透视距离，在实验2和4中，从眼睛到地面或墙壁的距离会缩短。随着距离和眼高的变化，目标向视线的倾斜也随之变化。我们认为线之间的表观角度随着缩短而增加，因为与低速的方位角相比，视觉低估了随着高度升高的缩短的快率。