How many clues are assessed during the Horizontal Gaze Nystagmus (HGN) test?

During the Horizontal Gaze Nystagmus (HGN) test, a total of six clues are assessed, which breaks down to three clues for each eye. The test assesses involuntary jerking of the eyes (nystagmus) as the eyes gaze to the side. These clues include:

1. The ability to follow a stimulus smoothly.

2. The appearance of distinct nystagmus at maximum deviation.

3. The onset of nystagmus prior to a 45-degree angle of gaze.

By focusing on both eyes, the overall evaluation provides a clearer picture of potential impairment. This procedure is essential within the context of the Standardized Field Sobriety Tests, as it is one of the most reliable indicators of alcohol impairment due to its ability to reflect the effects alcohol has on the central nervous system.