PHYSIOLOGICAL CLASS - INFORMATION PROCESSING
A person's ability to make crucial driving decisions, such as braking, steering, or changing lanes is affected by alcohol. Alcohol slows the rate of information processing by the brain. This effect has been noted on many different kinds of tasks even at the lowest levels of alcohol consumption. For example, a moderate alcohol dose (0.52 g alcohol/kg body weight) slowed subjects whose only task was to respond with the names of familiar, visually displayed objects.
If there are two or more stimuli and if several responses are possible, response times lengthen significantly. More complex tasks are even more severely degraded by alcohol.
Alcohol-impaired drivers require more time to read a street sign or to recognize and respond to a traffic signal than those who are not impaired. Consequently, they look at fewer sources of information and acquire less total information per unit of time. Because they must cope with the ongoing requirement to steer the vehicle, they restrict their looks to the center of the driving environment, and they may fail to see critical events occurring elsewhere.