What is the maximum number of clues that can be obtained from the Lack of Smooth Pursuit test in the HGN?

The Lack of Smooth Pursuit test in the Horizontal Gaze Nystagmus (HGN) assessment is designed to observe a specific aspect of eye movement that can indicate impairment. The correct answer is that you can derive one clue for each eye during the test. This means that when conducting the HGN test, the officer examines both the left and right eye individually to retrieve a total of two possible clues.

When evaluating for Lack of Smooth Pursuit, the officer looks for the ability of each eye to smoothly follow a moving stimulus, usually a pen or flashlight. If there is a noticeable lack of smooth pursuit in either eye, it counts as a clue indicating possible impairment. This method is rigorously applied to ensure that each eye's functioning is taken into account, thereby confirming the relevance of the observed eye movement.

These procedural details confirm that only one clue is obtained from the smooth pursuit observation of each eye, which leads to the total of two clues possible if both eyes exhibit a lack of smooth pursuit. Thus, each eye's performance during the test is critical for making accurate assessments regarding a person's sobriety.