Blinding Speed: The Effects of Relative Motion on Visual Resolution
Cole Gilbert

If you have ever tried to take a picture of something moving fast you are aware of the problems that arise from using too slow a shutter speed: the image is blurred and there is a general loss of contrast. The same problem is associated with the visual systems of animals, including humans, whenever there is relative motion between the observer and the object being observed. At slow speeds, viewing is typically fine. At higher speeds, such as during pursuit of prey or mates, blurring and loss of contrast can become a real problem for the pursuer if their photoreceptor cells and higher-order visual neurons are not fast enough.

In this Exploration, you will examine the physiological response properties of photoreceptors and visual neurons in insects, flies and perhaps beetles, using amplifiers, oscilloscopes, and computers to stimulate the eye and capture electrical signals from specific cells in the insect’s retina and brain. Then you will determine the temporal properties of such cells, e.g., how fast are they?, what sort of visual motion do they respond to?, all directions or only some?, do they respond to small objects or also large ones as well? You will also compare your own visual temporal sensitivity to that of the insect to determine which is faster. Hint: How difficult is it to sneak up on a fly?