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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