What does HGN stand for in the context of SFST?

In the context of Standardized Field Sobriety Tests (SFST), HGN stands for Horizontal Gaze Nystagmus. This test is a key component used by law enforcement to assess a driver's impairment due to alcohol consumption. Horizontal Gaze Nystagmus refers to the involuntary jerking movement of the eyes as they are moved outward and to the side. When a person is sober, their eyes should move smoothly without any jerking. However, when a person is impaired, the eyes will demonstrate noticeable jerking or nystagmus at certain angles, typically beyond 45 degrees from center.

This test is one of the standardized methods used for detecting impairment and is supported by scientific research that correlates the presence of horizontal gaze nystagmus with blood alcohol concentration levels. Understanding how this test works and its relevance to assessing impairment is vital for law enforcement officers trained in SFST. The other options presented do not accurately represent the terminology or the method used in this assessment, emphasizing the importance of recognizing the correct terminology in the context of SFST.