The friends and families of the participants like to gaze at the gays in their outrageous costumes for the Halloween Parade in West Hollywood.
When Jerry was watching the parade in San Francisco, it was hard not to gaze at the huge rainbow flag that the gays in the parade were waving.
A very low intensity light shines into one of the user's eyes. Reflections from the cornea and retina are picked up by a television camera.
As the direction of the person's gaze moves, the relative position of the two reflections changes, and the computer uses this information to determine th area at which the person is looking. The computer then executes the command.