arguably the most prevalent example of a stabilized inverted pendulum is a human being. a person standing upright acts as an inverted pendulum with his feet as the pivot, and without constant small muscular adjustments would fall over. the human nervous system contains an unconscious feedback control system, the sense of balance or righting reflex, that uses proprioceptive input from the eyes, muscles and joints, and orientation input from the vestibular system consisting of the three semicircular canals in the inner ear, and two otolith organs, to make continual small adjustments to the skeletal muscles to keep us standing upright. walking, running, or balancing on one leg puts additional demands on this system. certain diseases and alcohol or drug intoxication can interfere with this reflex, causing dizziness and disequilibration, an inability to stand upright. a field sobriety test used by police to test drivers for the influence of alcohol or drugs, tests this reflex for impairment.