From laboratory tests ensues a relatively small influence of ethanol on different functions which affect the ability to drive a motor vehicle. Under laboratory conditions ethanol protracts the simple reaction time surprisingly very little, at concentrations of 1g/kg, 1.28 times (5). Despite this the relative risk of a fatal accident of the driver of a motor car at ethanol concentrations of 0.5-0.9 g/kg is nine times greater as compared with a sober driver (19).The problem behavior theory tries to explain this apparent contradiction (9).

        Key words: ethanol - driver - ability to drive a motor vehicle - reaction time - problem behavior therapy