the
line, turn in a prescribed manner, and use the other foot to take several
small steps to complete the turn. The Walking Stage divides the subject’s
attention among a balancing task (walking heel-to-toe and turning); a small
muscle control task (counting out loud); and a short-term memory task
(recalling the number of steps and the turning instructions).
The
Walk-and-Turn test is administered and interpreted in a standardized manner,
i.e., the same way every time. Officers administering the Walk-and-Turn test
observe the suspect’s performance for eight clues:
•
can’t balance during instructions;
• starts too soon;
• stops while walking;
• doesn’t touch heel-to-toe;
• steps off line;
• uses arms to balance;
• loses balance on turn or turns incorrectly; and,
• takes the wrong number of steps.
Inability
to complete the Walk-and-Turn test occurs when the suspect:
•
steps off the line three or more times;
• is in danger of falling;
• cannot do the test.
Original
research shows that if a suspect exhibits two or
more of the clues, or cannot complete
the test, the suspect’s BAC is likely to be above 0.10. This criterion has
been shown to be accurate 68 percent of the time.
ONE-LEG
STAND
The One-Leg Stand test also has been validated through NHTSA’s
research program. It is a divided attention test consisting of two stages:
•
Instructions Stage; and,
• Balance and Counting Stage.
