Smooth Pursuit in The Absence of A Visual Target
Performing smooth pursuit without a moving visual stimulus is difficult, and typically results in a series of saccades. However, pursuit without a visible target is possible under some particular conditions, that show the importance of high-level functions in smooth pursuit maintenance. If you know which way a target will move, or know the target trajectory (because it is periodic for instance), you can initiate pursuit before the target motion actually starts, especially if you know exactly when the motion will start. It is also possible to maintain pursuit if a target momentarily disappears, especially if the target appears to be occluded by a larger object. Under conditions in which there is no visual stimulation (in total darkness), we can still perform smooth pursuit eye movements with the help of a proprioceptive motion signal (e.g. your moving finger).
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Famous quotes containing the words smooth, pursuit, absence, visual and/or target:
“It may seem strange that any road through such a wilderness should be passable, even in winter, when the snow is three or four feet deep, but at that season, wherever lumbering operations are actively carried on, teams are continually passing on the single track, and it becomes as smooth almost as a railway.”
—Henry David Thoreau (1817–1862)
“We hold these truths to be sacred and undeniable; that all men are created equal and independent, that from that equal creation they derive rights inherent and inalienable, among which are the preservation of life, and liberty, and the pursuit of happiness.”
—Thomas Jefferson (1743–1826)
“Baseball is the religion that worships the obvious and gives thanks that things are exactly as they seem. Instead of celebrating mysteries, baseball rejoices in the absence of mysteries and trusts that, if we watch what is laid before our eyes, down to the last detail, we will cultivate the gift of seeing things as they really are.”
—Thomas Boswell, U.S. sports journalist. “The Church of Baseball,” Baseball: An Illustrated History, ed. Geoffrey C. Ward, Knopf (1994)
“The chess pieces are the block alphabet which shapes thoughts; and these thoughts, although making a visual design on the chess-board, express their beauty abstractly, like a poem.... I have come to the personal conclusion that while all artists are not chess players, all chess players are artists.”
—Marcel Duchamp (1887–1968)
“Well gentlemen, this is it. This is what we’ve been waiting for. Tonight your target is Tokyo. And you’re gonna play ‘em the Star Spangled Banner with two-ton bombs. All you’ve got to do is to remember what you’ve learned and follow your squadron leaders. They’ll get you in, and they’ll get you out. Any questions? All right that’s all. Good luck to you. Give ‘em hell.”
—Dudley Nichols (1895–1960)