Primarily used by the California Highway Patrol, this test involves the test subject holding one hand in front of them. The subject is told to touch the tip of the thumb to the tip of each finger on that hand while counting "one, two, three, four, four, three, two, one." Completing these eight movements constitutes one "sequence." The test subject is told to perform three sequences and to count out loud.
Using the pads of the fingers instead of the tips of the fingers, failing to count out loud, mis-counting, or failing to perform three sequences will convince the officer that you have failed the test.