Subjective estimates of body tilt and the rod-and-frame test.

The existence of an illusion of self-tilt in the rod-and-frame test was demonstrated using a magnitude-estimation procedure. Subjects, seated in a tiltable chair, estimated their body tilt after being placed in one of 13 body tilt positions and while viewing a rod-and-frame display. A shift of the apparent body position occurred in the opposite direction of frame tilt. The results are consistent with earlier findings using the method of body and head adjustment.