Third-eye Rivalry

We showcase an optical phenomenon that we call “Third-eye Rivalry”. The effect is most easily induced by viewing one’s own reflection in a mirror. Using the pupil of the opposing eye as a fixation target, people can easily cross their eyes in free-fusion to experience vivid rivalry. The resulting percept is of a prominent central “third” eye and two peripheral faces rivalling for perceptual dominance. We illustrate the process of achieving third-eye rivalry and discuss historical connotations of the third eye in scientific and mystical contexts.