During the HGN test, what specific eye movement is being observed?

The correct answer focuses on the observation of nystagmus, which refers to the involuntary jerking movements of the eyes. During the Horizontal Gaze Nystagmus (HGN) test, law enforcement officers look for these jerking movements as the subject’s eyes are moved to the side. Nystagmus can be indicative of impairment, particularly in cases of intoxication. The presence of these jerking movements can signal that the individual may be under the influence of alcohol or certain drugs, thus helping officers assess impairment effectively.

Convergence, pupil dilation, and fixed gaze do not pertain to the specific eye movement being evaluated in the HGN test. Convergence refers to the ability of the eyes to move toward each other, which is not assessed in the HGN test. Pupil dilation can occur due to various reasons, but is not a focus of the HGN evaluation. Fixed gaze typically signifies that the eyes are locked in one position, which contrasts with the actively observed nystagmus in the test. Understanding nystagmus is crucial for interpreting the results of sobriety tests correctly and effectively.