Shifting Focus; November/December 2011; Scientific American Mind; by Susana Martinez-Conde and Stephen L. Macknik; 8 Page(s)

Look up from this page and scan the scene in front of you. Your eyes dart around, bringing different objects into view. As you read this article, your eyes jump to bring every word into focus. You can become aware of, and even control, these large movements of the eyes, which scientists call saccades. But even when your eyes are apparently fixed on something—say, on a tree, face or word—they are moving imperceptibly, underneath your awareness. And recent research shows that these minute, subconscious eye movements are essential for seeing.

If you could somehow halt these miniature motions, any image you were staring at would fade from view. In fact, you would be rendered blind for most of the day. Although these eye movements have long baffled scientists, only recently have researchers come to appreciate their importance. Indeed, we now have garnered strong evidence that the largest of these involuntary meanderings, the so-called microsaccades, are critical to everyday vision.