What is the HGN test in Rhode Island?

HGN is the Horizontal Gaze Nystagmus test, the first NHTSA standardized field sobriety test. The officer holds a stimulus about 12-15 inches from the driver's face and moves it slowly side to side, watching for involuntary eye jerking (nystagmus). The officer scores 6 possible clues. NHTSA studies claim 88% accuracy when administered properly, but the test is highly vulnerable to administration errors and medical false positives.