Leshan, L. L., & Laird, L. A. (1944). Projected light pattern maze. Journal of Comparative Psychology, 37(5), 287-288.
http://dx.doi.org/10.1037/h0062048
An apparatus is described which is designed to study "the weightings of the various sense fields used by the rat in learning a maze." A shadow maze pattern is projected from lantern slides and reflected by a mirror onto the surface of a table. The table top is wired for electrical shock. Animals are trained to stay in the shadow path and are punished if they leave it. One rat learned to make 2 successive left turns in 21 daily sessions of 6 trials per day. (PsycINFO Database Record (c) 2016 APA, all rights reserved)