Lab 6: Measuring Intoxication: What Do the Numbers Mean UW Biology of Addiction

What do the numbers mean? HGN The examiner looks for three indicators of impairment in each eye: ◦ if the eye cannot follow a moving object smoothly, ◦ if jerking is distinct when the eye is at maximum deviation, ◦ if the angle of onset of jerking is 45° of center or less Suspect likely has a BAC of 0.08 or greater if all three eye Considerations: Positive test may also indicate consumption of seizure medications, phencyclidine, a variety of inhalants, barbiturates, and other depressants. The more intoxicated the subject the smaller the Nystagmus angle tends to be HGN is considered the MOST reliable field sobriety test.

What do the numbers mean? WAT (Walk and Turn) The examiner looks to see if the suspect ◦ cannot keep balance while listening to the instructions, ◦ begins before the instructions are finished, ◦ stops while walking to regain balance, ◦ does not touch heel-to-toe, ◦ steps off the line, ◦ uses arms to balance, ◦ makes an improper turn, ◦ or takes an incorrect number of steps. NHTSA research indicates that 79% of individuals who exhibit two or more indicators in the performance of the test will have a BAC of 0.08 or greater So if you scored a 6/8 (51%)  you appear drunk enough to be arrested Alcohol can effect balance by altering the density of the fluid in the inner ear.

What do the numbers mean? One Leg Stand (OLS) The officer looks for four indicators of impairment, including ◦ swaying while balancing, ◦ using arms to balance, ◦ hopping to maintain balance, ◦ putting the foot down NHTSA research indicates that 83% of individuals who exhibit two or more such indicators in the performance of the test will have a BAC of 0.08 of greater Alcohol affects balance

What do the numbers mean? Correlation b/w testing positive for each test and the chance of having the specified BAC BAC.08BAC.10 HGN88%77% WAT8%79% OLS65%83%

What do the numbers mean? Stroop Test… secrets revealed;) Level 2= congruent ◦ Color of ink matches word Level 3= incongruent ◦ Different color ink than stated The additional time that is taken to name the ink color in the incongruent relative to the congruent condition is referred to as Stroop interference Why use distraction on the Stroop Test? Alcohol slows down processing of information… distraction add more “traffic” to this process

What do the numbers mean? Stroop Test is a measure of cognitive function Impaired individuals have a more difficult time with the Stroop test  demonstrates increased Stroop interference Typically younger subjects preform better than older subjects Native language could be a factor….

Wrap-Up Criticisms of the Field Sobriety Test? ◦ Distraction ◦ Inaccurate measuring w/o devices ◦ Nervousness Failing the test can lead to DUI even in absence of BA level None are 100% accurate Accurate enough to convict? Can sober people fail?