An extract on #drunk
Alcohol has a very significant effect on the functions of the body which are vital to driving and being able to function. Alcohol is a depressant, which mainly affects the function of the brain. Alcohol first affects the most vital components of the brain and "when the brain cortex is released from its functions of integrating and control, processes related to judgment and behavior occur in a disorganized fashion and the proper operation of behavioral tasks becomes disrupted." In all actuality alcohol weakens a variety of skills that are necessary to perform everyday tasks.
One of the main effects of alcohol is severely impairing a person's ability to shift attention from one thing to another, "without significantly impairing sensory motor functions." This indicates that people who are intoxicated are not able to properly shift their attention without affecting the senses. People that are intoxicated also have a much more narrow area of usable vision than people who are sober. The information the brain receives from the eyes "becomes disrupted if eyes must be turned to the side to detect stimuli, or if eyes must be moved quickly from one point to another."
Several testing mechanisms are used to gauge a person's ability to drive, which indicate levels of intoxication. One of these is referred to as a tracking task, testing handeye coordination, in which "the task is to keep an object on a prescribed path by controlling its position through turning a steering wheel. Impairment of performance is seen at BACs of as little as 0.7 milligrams per milliliter (mg/ml)." Another form of tests is a choice reaction task, which deals more primarily with cognitive function. In this form of testing both hearing and vision are tested and drivers must give a "response according to rules that necessitate mental processing before giving the answer." This is a useful gauge because in an actual driving situation drivers must divide their attention "between a tracking task and surveillance of the environment." It has been found that even "very low BACs are sufficient to produce significant impairment of performance" in this area of thought process.
A direct effect of alcohol on a person's brain is an overestimation of how quickly their body is recovering from the effects of alcohol. A study, discussed in the article "Why drunk drivers may get behind the wheel", was done with college students in which the students were tested with "a hidden maze learning task as their BAC [Blood Alcohol Content] both rose and fell over an 8-hour period." The researchers found through the study that as the students became more drunk there was an increase in their mistakes "and the recovery of the underlying cognitive impairments that lead to these errors is slower, and more closely tied to the actual blood alcohol concentration, than the more rapid reduction in participants' subjective feeling of drunkenness."
The participants believed that they were recovering from the adverse effects of alcohol much more quickly than they actually were. This feeling of perceived recovery is a plausible explanation of why so many people feel that they are able to safely operate a motor vehicle when they are not yet fully recovered from the alcohol they have consumed, indicating that the recovery rates do not coincide.
This thought process and brain function that is lost under the influence of alcohol is a very key element in regards to being able to drive safely, including "making judgments in terms of traveling through intersections or changing lanes when driving." These essential driving skills are lost while a person is under the influence of alcohol.