The second clue of the HGN test indicates what specific behavior?

The second clue of the Horizontal Gaze Nystagmus (HGN) test specifically indicates "distinct and sustained nystagmus at maximum deviation." This behavior refers to the observation of the eyes as they are moved to the outer edges of their range of motion. When the eyes are held at the far left and right positions, the presence of distinct and sustained nystagmus means that there is an involuntary jerking of the eyes that is observable and persists for a noticeable duration. This phenomenon is significant because it is a strong indicator of alcohol impairment; a sober individual typically will not exhibit this behavior.

Understanding this particular clue helps officers determine a subject's level of impairment. The other options described highlight various eye movement behaviors but do not capture the specific emphasis on the sustained aspect of nystagmus at maximum deviation, which is crucial for establishing impairment levels in the context of the HGN test.