For how long should one hold at maximum deviation during the HGN test?

During the Horizontal Gaze Nystagmus (HGN) test, the maximum deviation of the eye should be held for a duration of 4 seconds. This timeframe allows the officer to clearly observe any involuntary jerking of the eyes, known as nystagmus, which is indicative of impairment. Holding for this specific duration ensures that the officer has sufficient time to assess the characteristic movements of the eye at maximum deviation. Observing for too short a time might lead to misinterpretation of the results, while extending the duration unnecessarily could contribute to variability in the readings, making the assessment less reliable. Thus, 4 seconds is the optimal period recommended for maximizing accuracy in detecting potential alcohol or drug impairment during this critical field sobriety test.