ANGLES OF SHADOWS AS CUES FOR JUDGING THE DISTANCE OF SHADOW CASTING OBJECTS
Bem P. Allen · Perceptual and Motor Skills · 2000
40 participants were presented the six possible comparisons of four pictures of cylinders and their shadows. For each comparison, each participant was to decide which cylinder was most distant from a reference point. Overall 15 of the participants got all six judgments correct, an outcome that is exceedingly unlikely by chance.