However, you do not see this movement. This can be well demonstrated by looking in a mirror and saccading between the images of your two eyes in the mirror. You cannot see them rotating because vision is suppressed during the movement. Using mainly rods. Their role is secondary to the kinocilium .
Sustained responses are ones that are maintained or carry on as long as the stimulus is present.
Transient responses are to the onset and offset of stimuli and decay away, even if the stimulus is still present. A piece of glass is arranged so that part of it is directly on a surface and another part is high above the floor. This produces a visual cliff which can only be detected if a subject supported on the glass can perceive depth. A likely cue that they are using is accommodation. This was investigated by Gibson and Walk.