Instructions, illusory self-tilt and the rod-and-frame test

If an illusion of self-tilt is involved in rod-and-frame test performance, then instructions to adjust the rod to the body midline (egocentric instructions) should result in less rod adjustment error than the standard instructions for the rod-and-frame test to adjust the rod to the gravitational vertical. Two experiments were designed to examine this possibility. The results of the first experiment indicate that the tilted rod-and-frame display induces an illusion of self-tilt in the opposite direction. Significant differences between instructional conditions were found in the second experiment as expected. Other rod-and-frame studies are discussed in view of these findings.