Because of the high level of sensitivity that the eye’s retina has to hypoxia, symptoms are usually first experienced visually. As the retinal blood pressure decreases below globe pressure (usually 10–21 mm Hg), blood flow begins to cease to the retina, first affecting perfusion farthest from the optic disc and retinal artery with progression towards central vision. Skilled pilots can use this loss of vision as their indicator that they are at maximum turn performance without losing consciousness. Recovery is usually prompt following removal of "g"-force but a period of several seconds of disorientation may occur. Absolute incapacitation is the period of time when the aircrew member is physically unconscious and averages about 12 seconds. Relative incapacitation is the period in which the consciousness has been regained, but the person is confused and remains unable to perform simple tasks. This period averages about 15 seconds. Upon regaining cerebral blood flow, the G-LOC victim usually experiences myoclonic convulsions (often called the ‘funky chicken’) and often full amnesia of the event is experienced. Brief but vivid dreams have been reported to follow G-LOC. If G-LOC occurs at low altitude, this momentary lapse can prove fatal and even highly experienced pilots can pull straight to a G-LOC condition without first perceiving the visual onset warnings that would normally be used as the sign to back off from pulling any more "g"s.