The worst-affected age group was 25 to 34-year-olds, with almost a quarter admitting to regular memory blanks. Just 9 per cent of drivers aged over 65 said they suffered from the problem.
Edmund King, president of the AA, said the blanks may be due to drivers being distracted by phone calls, passenger conversations, listening to the radio or simply daydreaming.
He said: "Motoring memory blanks may be an indication that the driver is not concentrating on the road ahead.
"It is good practice as a driver to question yourself as to whether you could safely stop if a child walked out from behind that parked car. Many drivers also go on to autopilot when they are close to home after a long journey, and that is a good time to remind yourself to concentrate harder to get home safely."
According to government figures, the most common contributory factor in road accidents and casualties is people failing to look. The latest statistics show this occurred in 44 per cent of accidents in 2014, up from 32 per cent in 2005. Meanwhile, 6.9 million motorists have been found to lack confidence in their skills to the extent they believe they would fail a retake of their test.
Nearly a fifth of qualified drivers doubt they would be able to earn a pass because of their bad parking, turning and other practical skills. One in four pensioners think they would not pass.
Drivers from Newcastle upon Tyne in the North of England were the most apprehensive behind the wheel, with three out of 10 believing they would fail their test. Those from Edinburgh and Birmingham were the most confident with one in 10 admitting their licence may not be renewed.
The poll of 1,000 drivers was carried out by Young Driver, which provides driving lessons for teenagers.
