What effect can holding a gaze for insufficient time at maximum deviation have?

Holding a gaze for insufficient time at maximum deviation can compromise the validity of the test results. The Horizontal Gaze Nystagmus (HGN) test relies on the observation of eye movement characteristics, specifically at the point of maximum deviation from the center. This observation is critical because it allows the examiner to assess the presence and degree of nystagmus.

When the gaze is not held long enough, it can lead to a misinterpretation of the eye's behavior, potentially missing subtle signs that indicate intoxication or impairment. Observing the maximum deviation for an adequate amount of time ensures that the examiner can accurately detect involuntary jerking of the eyes, which is an indicator of the influence of alcohol or other drugs. Therefore, insufficient time at maximum deviation could invalidate the test by failing to provide a clear picture of the subject's eye movements, ultimately affecting the assessment of impairment.