The subject is assessed on the ability to understand and follow instructions as well as the ability to maintain balance for thirty seconds. Optokinetic nystagmus is also caused by watching alternating moving images, such as black and white spokes on a spinning wheel. Physiological nystagmus is so slight that it cannot be detected without the aid of instruments and it occurs in everyone. PAN II - The alcohol concentration is lower in the blood than in the vestibular system. Post-rotational nystagmus lasts for only a few seconds after a person stops spinning.
Rotational nystagmus occurs while the person is spinning.
SCRI has conducted subsequent field sobriety test validation studies as well as drug recognition evaluation studies. The results of this battery, usually administered along the roadside, contribute extensively to a law enforcement officer's decision to arrest a person for impaired driving. This test requires a person to take nine heel to toe steps down a straight line, turn and take nine heel to toe steps back up the line. The subject is assessed on the ability to understand and follow instructions as well as the ability to maintain balance during the instruction stage and walking stage. The system of fluid-filled canals located in the inner ear that assists in balance, coordination and orientation.