Which of the following is not listed as a DUI stimulus clue?

• A. Double vision
• B. Check for equal pupil size
• C. Resting Nystagmus
• D. Equal tracking

Answer: (A)

DUI stimulus clues are observable signs that officers look for during impairment assessments. Among the options, double vision is not a listed stimulus clue because it is a subjective symptom the driver would report, not something the officer can directly observe during the test. The other items are observable cues: equal pupil size is checked as a sign of normal or abnormal pupil response, resting nystagmus is an involuntary eye movement that can indicate impairment, and equal tracking refers to the eyes moving smoothly and together—impaired tracking is a common observable clue. So double vision isn’t a standard cue the test uses, which is why it’s the correct choice.