·may slow down body function? 71．______
·can lead to the drivers' distorted perception of reality? 72．______
·may influence the drivers' vision negatively? 73．______
·is psychologically addictive to those chronic uses? 74．______
·can cause the impairment of driving? 75．______
·can cause difficulty focusing? 76．______
·can make drivers dissociate from the environment? 77．______
·can make drivers easily irritated? 78．______
·can affect how drivers think．feel and act? 79．______
·may stimulate drivers to flee in their cars? 80．______
A The term “hallucinogen” describes any drug that radically changes a person's mental state by distorting the perception of reality to the point where，at high doses，hallucinations occur．Normal sensitivity is usually restored after abstaining for several consecutive days．Chronic users may also become psychologically dependent on hallucinogens．Psychological dependence exists when a drug is so central to a person's thoughts，emotions，and activities that the need to continue its use mats to a craving or compulsion．
According to the National Survey on Drug Abuse，four million Americans used hallucinogens in 1982．Presumably most of them drive．Paul Fishbein of Phoenix House in New York City，one of the nation's largest residential drug-treatment facilities，describes the driver-impairing impact of phencyclidine(PCP or “angel dust”)，a depressant with hallucinogenic effects：“After the first few hits(drags)of a PCP-laced joint,”he explains,“you have to look at the floor to see where your feet are．A few more hits and you dissociate from the environment．When a person drives under the influence of PCP，LSD or other hallucinogens，he may stop in the middle of a freeway to look at his map．Everything else going on him is not part of his experience—so why should he care about other cars?”
{{B}}B{{/B}} The changes in a person's perception, mood，and thinking during cocaine intoxication are particularly relevant to driving skills．
The most dramatic effects of cocaine with respect to driving are on vision．Cocaine may cause a higher sensitivity to light，halos around objects，and difficulty focusing．Users have also reported blurred vision，glare problems，and hallucinations，particularly “snow lights”—weak flashes or movements of light in the peripheral field of vision，which tend to make drivers swerve toward or away from the lights．Some users have also reported auditory hallcucinations(e.g. ring bells)and old factory hallucinations(e.g. smell of smoke or gasoline)．
Many users say that cocaine actually improves their driving ability，which is not surprising because the drug induces euphoria and feelings of increased mental and physical abilities．Such self-reports must be accepted with caution，however，since these effects of cocaine are short-lived and are often followed by fatigue and lassitude．
Cocaine can also heighten irritability，excitability，and startle response．Users have reported that sudden sounds，such as horns or sirens，have caused them severe anxiety coupled with rapid steering or braking reactions，even when the source of the sound was not in the immediate vicinity of their vehicles．Suspiciousness，distrust，and paranoia—other reactions to cocaine—have prompted users to flee in their cars or drive evasively．Everyone surveyed reported attention lapses while driving and ignoring relevant stimuli such as changes in traffic signals．
In May 1983 Dr．Mark Gold，medical director of Fair Oaks Hospital in Summit，N.J.，set up a telephone hot line for cocaine users，which in eight months received some 220,000 calls．“Cocaine users tell us they have such a feeling of power and mastery when they're on the drug that they think they can do things with the car they can't do，”says Gold．“With cocaine，” exulted a 30-year-old ad executive，“I can go a hundred miles an hour and give death a finger in the eye．” Such drivers present a horrifying highway hazard．
{{B}}C{{/B}} What does alcohol do to a driver that makes driving so dangerous? How does it affect driving skills? Alcohol impairs driving skills．Alcohol is a depressant drug that slows down body functions．The amount of alcohol in the blood at any point in time is referred to as the Alcohol Concentration(AC)level．The greater the amount of alcohol in the blood the higher the AC level and greater the impairment of driving．Even at very low AC levels(.01 -.04)，important body functions and skills can be affected．At higher AC levels(.05 and above)these functions become greatly impaired．Those functions most directly related to driving include coordination and balance，vision，steering，perception，processing of information，attention and judgment．It is important to remember that there is no safe level of alcohol that a person can assume will not impair driving performance．Alcohol can affect how we think，feel and act．