October 29, 2015

DWI Detection and Standardized Field Sobriety Testing Clue Number 3 Onset of Nystagmus Prior to 45 Degrees 8-51

Session 8 - Concepts and Principles of the Standardized Field Sobriety Tests (SFST)
DWI Detection and Standardized Field Sobriety Testing
Clue Number 3
Onset of Nystagmus Prior to 45 Degrees
8-51
Clue No. 3: Onset of Nystagmus Prior to 45 Degrees
Once again, position the stimulus approximately 12 - 15 inches (30 - 38 cm) in front of
subject's nose and slightly above eye level.
The angle of onset of nystagmus is simply the point at which the eye is first seen
jerking.
Examples: With someone at a very high BAC (0.20+), the jerking might begin almost
immediately after the eye starts to move toward the side. For someone at 0.08 BAC,
the jerking might not start until the eye has moved nearly to the 45 degree angle.
Generally speaking, the higher the BAC, the sooner the jerking will start as the eye
moves toward the side.
If the jerking begins prior to 45 degrees, that person’s BAC could be 0.08 or above.
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Session 8 - Concepts and Principles of the Standardized Field Sobriety Tests (SFST)
DWI Detection and Standardized Field Sobriety Testing
Clue Number 3 (Cont.)
Onset of Nystagmus Prior to 45 Degrees
8-52
It is not difficult to determine when the eye has reached the 45 degree point, but it does
require some practice.
If you start with the stimulus approximately 12 - 15 inches (30 - 38 cm) directly in front of
the nose, you will reach 45 degrees when you have moved the stimulus an equal
distance to the side. Two other important indicators can be used to determine if the eye
is within 45 degrees.
At 45 degrees, some white usually will still be visible in the corner of the eye (for most
people).
If you started with the stimulus approximately 12 - 15 inches (30 - 38 cm) in front of the
subject, when you reach 45 degrees the stimulus will usually be lined up with, or slightly
beyond, the edge of the subject's shoulder.
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Session 8 - Concepts and Principles of the Standardized Field Sobriety Tests (SFST)
DWI Detection and Standardized Field Sobriety Testing
Mechanics of
Clue Number 3
8-53
The Mechanics of Clue No. 3
The stimulus is positioned approximately 12 - 15 inches from (30 - 38 cm) subject's
nose and slightly above eye level. It is necessary to move the stimulus slowly to identify
the point at which the eye begins to jerk.
Start moving the stimulus towards the right side (left eye) at the speed that would take
approximately 4 seconds for the stimulus to reach the edge of the subject's shoulder.
As you are slowly moving the stimulus, watch the eye carefully for any sign of jerking.
When you see the jerking begin, immediately stop moving the stimulus and hold it
steady at that position.
With the stimulus held steady, look at the eye and verify that the jerking is continuing.
If the jerking is not evident with the stimulus held steady, you have not located the point
of onset. Therefore, resume moving the stimulus slowly toward the side until you notice
the jerking again.
When you locate the point of onset of nystagmus, you must determine whether it is prior
to 45 degrees.
Notes:_______________________________________________
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Session 8 - Concepts and Principles of the Standardized Field Sobriety Tests (SFST)
DWI Detection and Standardized Field Sobriety Testing
Mechanics of
Clue Number 3 (Cont.)
8-54
Verify that some white is still showing in the corner of the eye.
Examine the alignment between the stimulus and the edge of the subject's shoulder.
Start moving the stimulus towards the left side (right eye) at the speed that would take
approximately 4 seconds for the stimulus to reach the edge of the subject's shoulder.
As you are slowly moving the stimulus, watch the eye carefully for any sign of jerking.
When you see the jerking begin, immediately stop moving the stimulus and hold it
steady at that position.
With the stimulus held steady, look at the eye and verify that the jerking is continuing.
If the jerking is not evident with the stimulus held steady, you have not located the point
of onset. Therefore, resume moving the stimulus slowly toward the side until you notice
the jerking again.
When you locate the point of onset of nystagmus, you must determine whether it is prior
to 45 degrees.
Verify that some white is still showing in the corner of the eye.
Examine the alignment between the stimulus and the edge of the subject's shoulder.
Session 8 - Concepts and Principles of the Standardized Field Sobriety Tests (SFST)
DWI Detection and Standardized Field Sobriety Testing
Live Demonstration
Clue Number 3
8-55
Live Demonstration of the Mechanics of Clue No. 3
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Session 8 - Concepts and Principles of the Standardized Field Sobriety Tests (SFST)
DWI Detection and Standardized Field Sobriety Testing
Participant Practice
Clue Number 3
8-56
Participant practice of the mechanics of Clue No. 3
Coaching and critiquing participants practice.
Participant led demonstration.
Session 8 - Concepts and Principles of the Standardized Field Sobriety Tests (SFST)
DWI Detection and Standardized Field Sobriety Testing
45 o
45 Degree Template
8-57
Training Aid: The 45 Degree Template
A training aid has been provided to help you practice estimating a 45 degree angle.
• The outline of a square, with its diagonal line, gives us a 45 degree angle.
• This outline, or template, is provided for practice only.
• It is not to be used with actual DWI subjects.
To use the template, have your training partner hold the corner of the square under the
nose.
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Session 8 - Concepts and Principles of the Standardized Field Sobriety Tests (SFST)
DWI Detection and Standardized Field Sobriety Testing
45 Degree Template (Cont.)
45 o
8-58
When you line up your stimulus with the diagonal line, your partner will be looking along
a 45 degree angle.
Session 8 - Concepts and Principles of the Standardized Field Sobriety Tests (SFST)
DWI Detection and Standardized Field Sobriety Testing
Participant Practice
45 o
8-59
Coaching and Critiquing Participants' Practice
Participant led Demonstration
Session 8 - Concepts and Principles of the Standardized Field Sobriety Tests (SFST)
DWI Detection and Standardized Field Sobriety Testing
Horizontal Gaze Nystagmus
Test Criterion
4 or more clues indicates
BAC above 0.08 (88% accurate)
8-60
Test Interpretation
Based upon the original developmental research into Horizontal Gaze Nystagmus, the
criterion for this test is 4.
If a person exhibits at least 4 out of the possible 6 clues, the implication is a BAC above
0.08.
Using this criterion, the test is 88% accurate.
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HS 178 R5/13 38 of 62 Source: DWI Detection and
Standardized Field
Sobriety Testing
March 2013 Edition

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