SFST Observation Skills 3 — Questions and Answers
Question 1: During the HGN test, at what point does the officer check for 'onset of nystagmus prior to 45 degrees'?
- While moving the stimulus at maximum deviation
- While moving the stimulus slowly from center toward the side (Correct answer)
- Only during the smooth pursuit check
- After checking for lack of smooth pursuit and distinct nystagmus at maximum deviation
Correct answer: While moving the stimulus slowly from center toward the side
The officer checks for onset prior to 45 degrees during the lateral pass, moving the stimulus slowly from center toward the edge of the visual field.
Question 2: A suspect on the One-Leg Stand test puts their foot down twice and sways but does not hop. How many clues are scored?
- One clue (sways)
- Two clues (sways and puts foot down)
- Three clues (two foot-down instances and swaying)
- Two clues (puts foot down counts once, plus swaying) (Correct answer)
Correct answer: Two clues (puts foot down counts once, plus swaying)
Puts foot down is scored as one clue regardless of frequency, and swaying is a separate clue, for a total of two clues.
Question 3: What is the primary purpose of the 'divided attention' concept in SFST administration?
- To confuse the suspect into making mistakes
- To test the ability to perform mental and physical tasks simultaneously, which is impaired by alcohol (Correct answer)
- To demonstrate that the suspect can follow simple instructions
- To measure reaction time exclusively
Correct answer: To test the ability to perform mental and physical tasks simultaneously, which is impaired by alcohol
Divided attention tests reveal impairment because alcohol degrades the ability to perform simultaneous mental and physical tasks.
Question 4: If a suspect wears bifocals or trifocals, how should the officer adjust the HGN test?
- Have the suspect remove glasses before testing (Correct answer)
- The test cannot be administered to suspects with bifocals
- Raise the stimulus higher to compensate for the lens division
- No adjustment is needed — administer the test normally
Correct answer: Have the suspect remove glasses before testing
NHTSA guidelines recommend having suspects remove glasses before the HGN test, as bifocals can interfere with proper eye tracking observation.
Question 5: During the Walk-and-Turn test, a suspect stops walking midway through the first nine steps. The officer should:
- Immediately score a clue and ask the suspect to restart
- Score a clue for stopping while walking and allow the suspect to continue (Correct answer)
- End the test and note the inability to complete
- Offer a second attempt without scoring the first
Correct answer: Score a clue for stopping while walking and allow the suspect to continue
Stopping while walking is a scorable clue, and the officer allows the suspect to continue to gather additional observations.
Question 6: An officer observes a suspect's pupils appear unequal in size. What should the officer do with this observation?
- Score it as an additional HGN clue
- Note it in the report as it may indicate a medical condition or head injury (Correct answer)
- Ignore it as SFST tests do not address pupil size
- Conclude the suspect is under the influence of stimulants
Correct answer: Note it in the report as it may indicate a medical condition or head injury
Unequal pupils (anisocoria) can indicate a medical condition or head injury and should be documented, as it may also explain other observed signs.
Question 7: When administering the OLS test, what should the officer do if the suspect begins counting faster than one number per second?
- Stop the test and restart with clearer instructions
- Allow it to continue — counting speed is not a clue
- Remind the suspect to count at one number per second (Correct answer)
- Score it as an additional clue for non-compliance
Correct answer: Remind the suspect to count at one number per second
The officer should remind the suspect to count at the instructed pace to ensure the test is properly timed, as 30 seconds is the standard duration.
SFST Observation Skills 3
During the HGN test, at what point does the officer check for 'onset of nystagmus prior to 45 degrees'?