SFST Evaluation Factors 3 — Questions and Answers
Question 1: In the SFST battery, the correct sequence for administering the three standardized tests is:
- HGN, Walk-and-Turn, One-Leg Stand (Correct answer)
- Walk-and-Turn, HGN, One-Leg Stand
- One-Leg Stand, Walk-and-Turn, HGN
- HGN, One-Leg Stand, Walk-and-Turn
Correct answer: HGN, Walk-and-Turn, One-Leg Stand
NHTSA's validated sequence is HGN first, followed by Walk-and-Turn, then One-Leg Stand.
Question 2: What BAC threshold did NHTSA research use to validate the SFST battery's accuracy predictions?
- 0.08% BAC (Correct answer)
- 0.05% BAC
- 0.10% BAC
- 0.15% BAC
Correct answer: 0.08% BAC
The SFST battery was validated against the 0.08% BAC per se limit currently adopted in all U.S. states.
Question 3: Which of the following is NOT one of the eight clues scored on the Walk-and-Turn test?
- Sways side to side during instruction phase (Correct answer)
- Starts before instructions are finished
- Steps off the line
- Raises arms more than 6 inches
Correct answer: Sways side to side during instruction phase
Swaying side to side during the instruction phase is not one of the eight official clues; the eight clues are specific movements during test execution.
Question 4: When an officer observes a suspect with resting nystagmus before the HGN test begins, this finding most likely indicates:
- A neurological condition or very high level of CNS depressant influence (Correct answer)
- Normal variation unrelated to impairment
- An error in the officer's stimulus speed
- That the suspect is faking the nystagmus
Correct answer: A neurological condition or very high level of CNS depressant influence
Resting nystagmus (eye jerking at center gaze with no stimulus) can indicate neurological pathology or extremely high levels of CNS depressant impairment.
Question 5: An officer is administering the One-Leg Stand and the suspect raises their arms 8 inches from their sides. How many clues does this single action represent?
- One clue — raises arms (Correct answer)
- Two clues — raises arms and loses balance
- No clues if the suspect does not fall
- Three clues because it violates multiple instructions
Correct answer: One clue — raises arms
Raising arms more than 6 inches is counted as one distinct clue regardless of the degree to which they are raised.
Question 6: The 'divided attention' concept in SFSTs is significant because impaired drivers typically:
- Struggle to simultaneously process mental and physical tasks (Correct answer)
- Perform better on physical tasks when mentally occupied
- Refuse to attempt divided-attention tasks entirely
- Show divided-attention deficits only at BACs above 0.15%
Correct answer: Struggle to simultaneously process mental and physical tasks
Alcohol impairment reduces the brain's capacity to simultaneously handle both cognitive instructions and physical execution, which SFSTs are specifically designed to reveal.
Question 7: How many clues on the HGN test, out of a maximum of six, indicate that a suspect's BAC is likely at or above 0.08%?
- Four or more clues (Correct answer)
- Two or more clues
- Six clues (all present)
- Three or more clues
Correct answer: Four or more clues
NHTSA research determined that four or more HGN clues out of six correlates with a BAC at or above 0.08% with approximately 88% accuracy.
SFST Evaluation Factors 3
In the SFST battery, the correct sequence for administering the three standardized tests is: