Eye tracking white sclera (limbus tracking). It presents another challenge for vertical eye movements due to obstruction of eyelids. Eye-tracking setups vary greatly: some are head-mounted, some require the head to be stable (for example, with a chin rest), and some function remotely and automatically track the head during motion. Most use a sampling rate of at least 30 Hz. Although 50/60 Hz is more common, today many video-based eye trackers run at 240, 350 or even 1000/1250 Hz, speeds needed in order to capture fixational eye movements or correctly measure saccade dynamics. Eye movements are typically divided into fixations and saccades
The Eye of the Sibyl The Eye of the Sibyl "The Eye of the Sibyl" is a science fiction short story by American writer Philip K. Dick. It was written sometime around 1975, but not published until 1987 when it was included in volume 5 (subtitled "The Little Black Box") of "The Collected Stories of Philip K. Dick", and has been reprinted since in other editions of this book such as the U.S. edition "The Eye of the Sibyl and Other Stories" . This is said to have been Dick's first piece of fiction for publication after his "2-3-74" experience that was the basis for