Humming causes the eye to vibrate and this can produce a strobo-scopic effect when a rotating black and white strobe disk is viewed in non-fluctuating light.

Suppose that we attached lenses to the eyes of a newborn child, lenses having the property of reversing right-left and up and down. Suppose, also, that the child wore the lenses through childhood, boyhood, and young manhood. What would happen if these inverting lenses were finally removed on his twenty-fifth birthday? Would he be nauseated and unable to reach and walk and read?

Such an experiment is out of the question, of course. Yet another experiment was made: a young man was persuaded to wear inverting lenses for 30 days, and his experiences are reported here. His continued progress, after an initial upset, suggests that new perceptions do develop in the same way as the original perceptions did. Life situations suggest the same thing. Dentists learn to work via a mirror in the patient's mouth until the action is automatic. In the early days of television, cameramen had to "pan" their cameras with a reversed view. Later the image in the camera was corrected to correspond with the scene being panned. The changeover caused considerable confusion to cameramen until they learned appropriate visual-motor coordinations. Fred Snyder, the subject of our upside-down experiment, found himself in a similar predicament, at least for a time.

Pc Austin said that when he pulled over the car, Aziz, who wore dark glasses, was fumbling with the controls. When asked if he noticed anything about Aziz he replied: "I did — he didn't have any eyes."