The next field sobriety test is the walk-and-turn. This test and the next one are based on the concept of divided attention. These tests divide the driver’s attention between a physical task and a mental task. The physical tasks include balance and coordination. The mental tasks include comprehension of verbal instructions, recall of memory, and processing information. Divided attention tests happen because a person under the influence may be able to perform one task but not both. These tests divide the driver’s attention between two things at once. This checks for impairment because operating a motor vehicle requires divided attention.

Divided Attention

The walk-and-turn test divides the driver’s attention between balancing, counting out loud, recalling the number of steps and turning. This happens according to the police officer’s instructions. This test must be performed on a hard, dry, level, non-slip surface. There must be enough room for the driver to be able to complete nine heel-to-toe steps. Some of the issues with the validity of this test are when it is conducted in the winter with wind and weather conditions preventing proper administration. DUI detection training calls for a straight line. This line must be clearly visible. However, police officers are also taught that the test can be performed parallel to the curb. This can happen provided the driver is in no physical danger. An officer may prevent the driver from taking the test or stop the test for safety reasons.

When Not to Give the Test

Some people clearly shouldn’t take this test. Even the average sober person would have difficulty performing it. Persons over the age of 65 or more than 50 pounds overweight will have increased difficulty. A person who has any physical impairment that would affect the ability to balance also should not take this test. Police officers must take medical issues into account when developing probable cause to make an arrest.

Anyone wearing heels more than two inches high should get the opportunity to remove his or her shoes. The reason for this is obvious. An extended heel can affect a person’s ability to balance and obstruct any validity to the test results. People who have vision issues such as not being able to see out of one eye may also have problems with this test. This is due to poor depth perception.

Test Stages

The walk-and-turn test consists of two parts. There is the instructions stage and the walking stage. The instructions stage is designed to divide the driver’s attention between balancing and listening to the police officer. The driver must stand with feet in the heel-to-toe position. They must keep arms at the sides, all while listening to the police officer’s instructions. The police officer needs to follow training and procedure during this stage. If they don’t it can affect the validity of the test.

While the driver is taking this test, the police officer must observe the driver from three to four feet away. The police officer must remain motionless. If the police officer is too close or creates a distraction with excessive motion, this could cause the driver make errors. These errors might not be made otherwise. This issue can decrease the validity of the test. The police officer has to give explicitly clear verbal instructions, supplemented with an actual demonstration of the test. Without the demonstration, instructions alone can discredit the test results. The police officer has to get confirmation of the driver’s understanding of the instructions. If the officer doesn’t confirm the driver’s understanding of the instructions each time an instruction is given, the results of the test may be invalid.