ABSTRACT
Five weeks ago I received a letter from Dr. Volkmann (whom I had not yet met at that time) asking me to address myself to the question of the role of eye movements in the maintenance of a phenomenally clear and stable world. That letter came as a shock. I am not sure that the answer to this question is known to God (Jones, 1966); perhaps only to Leon Festinger (Marquis, 1972). I had not yet met either of these distinguished persons and knew no one to whom I could turn. But after a few weeks of thinking about the question and discussing it with several young collaborators, who had both ideas and the energy to do new experiments, I am ready to attempt a tentative answer. Before answering, however, I must make a few observations about human eye movements-these observations have influenced the answer that I will give.
