Knowing when to say when: a simple assessment of alcohol impairment.

The use of writing samples as indices of alcohol impairment was explored. Students at a campus fraternity party wrote a sentence and their signatures before and after consuming alcohol (in beer and mixed drinks). Later, undergraduate and graduate students attempted to discriminate between pre- and postparty handwriting samples. The average percentage of correct discriminations of entrance and exit writing samples was 83.7% for sentences and 67.5% for signatures, and the percentage of correct discriminations increased directly with the blood alcohol concentration of the partier who gave the writing sample. When a partier's blood alcohol concentration reached 0.15, all of the judges accurately discriminated 90% or more of the sentences, and 25 of the 28 judges correctly discriminated at least 80% of the signatures. All of the judges correctly discriminated at least 90% of the 18 sentences written by partiers with a blood alcohol concentration of 0.12 or more. Implications of these findings for reducing the risk of driving while intoxicated are discussed, as well as directions for follow-up research.