In the context of SFSTs, what does HGN stand for?

HGN stands for Horizontal Gaze Nystagmus, which refers to a specific eye movement that is used as one of the standardized field sobriety tests (SFST) to assess a driver's level of impairment, particularly regarding alcohol consumption. During the HGN test, an officer observes the involuntary jerking of the eyes as they follow a stimulus (typically a pen or flashlight) horizontally. This physiological reaction can indicate the presence of certain substances in the system, as alcohol and other drugs can significantly affect eye movement control.

The correct understanding of HGN is vital for law enforcement officers because it serves as a crucial indicator of a person's impairment status. Recognizing the differently themed options helps clarify that only "Horizontal Gaze Nystagmus" accurately describes the test used in SFST protocols. The other terms listed do not correspond to this recognized method of testing and may misrepresent the nature of the eye movements being assessed in the context of DUI testing.