A Finger-tapping Test for Judging Intoxication

Legally speaking, drunkenness is defined as a level of alcohol intoxication that boosts the body’s blood-alcohol level to 0.08 percent or higher. However, the impairing effects of drinking begin long before this level.

Judging intoxication better could help people to slow down and potentially prevent serious alcohol-related harm.

In a 2014 Alcoholism: Clinical & Experimental Research study, researchers from the State University of New York at Binghamton sought to determine the most accurate way an individual can subjectively tell if he or she is becoming intoxicated.

What Effect Does Alcohol Have?

Alcohol produces intoxication by altering normal function in the central nervous system, which contains both the brain and the spinal cord. This process begins when a person consumes more alcohol than his or her body can break down in a short amount of time. In turn, over consumption leads to a buildup of alcohol in the blood; gradually, alcohol in the bloodstream will travel to the brain and trigger the onset of the changes that account for drunkenness. Not all people get drunk at the same speed when they consume the same amount of alcohol.

Factors that can alter the rate of alcohol processing and drunkenness include the rate at which alcohol intake occurs, being male or female, being young or old, ethnic or racial differences in alcohol sensitivity, genetic differences in alcohol sensitivity within a racial or ethnic group, a drinker’s level of physical fitness, how much food a drinker has eaten and whether or not a drinker takes certain prescription medications or uses illicit/illegal drugs.

Different Levels of Drunkenness

Typically, alcohol first produces a noticeable intoxicating effect when the average person’s blood-alcohol level reaches 0.02 percent. Signs and symptoms of intoxication at this stage include a relaxed feeling, unusual changes in mood, a partial decline in clear thinking and a slight rise in body temperature. When the average person’s blood-alcohol level reaches 0.05 percent, additional signs and symptoms of intoxication appear, including such things as a further reduction in clear thinking, a lowering of personal inhibition, unusually over-the-top behavior and a reduced ability to maintain alertness.

The onset of legal drunkenness (a blood-alcohol level of 0.08 percent) produces further signs and symptoms of intoxication that include an even greater decline in clear thinking, a significantly reduced ability to use other conscious mental skills, serious impairment of muscle coordination and a diminished capacity to maintain awareness of one’s surroundings. As blood-alcohol levels rise past the point of legal drunkenness, more and more severe forms of mental and physical incapacitation begin to arise. For instance, a person with a blood-alcohol level of 0.15 percent will appear extremely intoxicated. A blood-alcohol level of 0.30 percent commonly produces unconsciousness; a blood-alcohol level of 0.40 percent can produce a coma and potentially lead to death.

How to Detect Drunkenness

In the study published in Alcoholism: Clinical & Experimental Research, the SUNY Binghamton researchers used an examination of 280 people between the ages of 18 and 32 to determine the best way an individual can detect the beginning of an impairing level of drunkenness. They undertook this project out of a belief that self-awareness of impending intoxication is critical to making the decision to stop drinking before serious alcohol-related harm can occur. The study participants were enrolled in the project as they left bars where they had consumed alcohol. The researchers tested each participant’s degree of intoxication with a breathalyzer, performed a procedure designed to detect changes in muscle speed, asked each participant to describe his or her level of drunkenness and also asked each participant a series of additional interview questions.

The researchers concluded that three factors account for people’s subjective viewpoint of their degree of drunkenness: their experience of the stimulating effects of alcohol consumption, their experience of the sedating effects of alcohol consumption and their actual blood-alcohol level. Since intoxication produces both mental and physical effects, an individual can potentially attempt to gauge his or degree of intoxication by tracking either mental or physical changes in normal function. The researchers compared the accuracy of subjectively judging drunkenness by noting changes in normal thinking to the accuracy of subjectively judging drunkenness by noting a simple decline in the ability to tap one’s fingers against a hard surface. They concluded that the basic finger-tapping test matches up with a person’s actual blood-alcohol level much better than any changes in normal thought processes.

The authors of the study published in Alcoholism: Clinical & Experimental Research note that their project echoes earlier findings on subjective drunkenness obtained in a laboratory setting. Since their work was performed in more real-world conditions, they believe it contributes substantially to the overall body of scientific knowledge and understanding.

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