Proprioception and the Field Sobriety Test

Knowing next week is Thanksgiving Break and the holidays are coming up, some of you are asking me to review our discussion on proprioception and talk about field sobriety tests. No, I’m not going to tell you how to beat a field sobriety test.

Proprioception

We talked about proprioception as a general sense, like light touch and pressure. It starts with receptors embedded in the skeletal muscles and joints. It tells the brain where your body is in space without you having to look at it.  The afferent nerves carry these impulses, primarily to the cerebellum, where it’s integrated with other info, especially from the ear (remember the vestibular parts that sense where your head is in space). Both proprioception and vestibular parts help you keep your balance.

Field Sobriety Tests

Some of the field sobriety tests focus on the lack of coordination alcohol causes in the brain. There are 3 “standard” field sobriety tests (SFST), described by the National Highway Transportation Safety Administration (NHSTA) and has some correlation to how drunk you are:

  • One-leg stand
  • Walk and turn
  • Horizontal Gaze Nystagmus Test

The one-leg stand and walk and turn are “divided attention tests.” For the one-leg stand, you stand with one foot off the ground while following other officer commands, like counting aloud. In walk-and-turn, you take 9 steps, heel-to-toe, along a straight line. The officer is looking for signs of impairment such as swaying, losing balance, using your arms too much to balance, not following directions, etc. You’re using multiple parts of the brain, including the parts that help to keep your balance like proprioception. They say that if you’re drunk, your brain can’t coordinate such complex tasks as well.

The nystagmus test is really an examination of the eyes. The officer will ask you to follow a light or a finger. Nystagmus is a twitching where you’re not following the object in a smooth manner. This is related to the vestibular receptors in the ear and how it’s interpreted by the brain.

There are other “non-standard” tests they use, including one I demonstrate (badly) in class as part of describing propioception: the Romberg test. In the Romberg stationary balance test, you stand, feet together, head back and look at the sky or close your eyes while holding your arms out to the side. Again, they are watching for you to lose your balance. This test is also used by medical professionals and uses the idea that you need 3 senses to keep your balance: proprioception, vestibular (receptors in the ear tell your brain where your head is in space) and

Officers can add the finger-to-nose test: while you tip your head back with your eyes closed, you touch the tip of your nose with the tip of your index finger. People normally may miss their nose by no more than 20 millimeters, while if you are impaired, you might fail the test because your body has difficulty locating your arms in space relative to your nose.

Other non-standard field sobriety tests include: reciting part of the alphabet, the finger count (touch each finger of the hand to the thumb and counting the finger number with each touch), count backwards from a number, recite the alphabet, and counting the number of fingers that the officer raises.

Hope I scared you enough. Don’t Drink and Drive. Use those “Tipsy Tows” and AAA. Don’t risk it. It’s expensive – I know, my brother’s a DUI attorney!

Online References.

Advertisements

One comment

  1. I watched as a guy was arrested for a hit-and-run. They (Costa Mesa PD) only did the nystagmus test with him, and then put him in the back of the squad car.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: