The main sequence, a tool for studying human eye movements

The astronomical term “main sequence” has been applied to the relationships between duration, peak velocity, and magnitude of human saccades over a thousandfold range of magnitude. Infrared photodiodes aimed at the iris-sclera border and a digital computer were used in experiments to derive the main sequence curves. In the pulse width modulation model, the duration of the controller signal pulse determines saccadic amplitude and peak velocity. The high-frequency burst of the oculomotoneurons needs to be only one-half the duration of the saccade, because of the “apparent inertia” of the eyeball.