The Sander illusion as a function of relative space and component lines

Geometrical illusions can affect time-to-contact estimation and mimed prehension.

“…monitor. Displays consisted of black-on-white drawings of a Sander parallelogram with the diagonals omitted; the latter results in a greater magnitude of illusion compared with the standard figure (Cooper et al, 1972; refer to Figure 1). The sides and tops of the figure were 2.25° and 6.36°, respectively.…”

“…We selected the Sander parallelogram illusion for several reasons. First, the magnitude of illusion is relatively large (often 20-25%), is comparable to the magnitude of the Mueller-Lyer illusion (25-30%), and increases when the diagonals are removed (Cooper, Runyon, Tatz, & Heimer, 1972;Coren & Girgus, 1978). Second, the Sander illusion permitted a comparison of performance on the different tasks without modification of the parallelogram; that is, the informational context was the same across tasks.…”