A university research team has found that antilock brakes and airbags don’t actually reduce accidents or injuries, because motorists are prone to drive more aggressively thinking they are safe in their vehicles. The findings come from a Purdue University study of vehicle accidents in Washington State over the past five years, showing that innovations designed to improve safety also make drivers less vigilant.

The behaviour is labelled “offset hypotheses” and its effect counters the modest technological benefits of airbags and antilock brakes. Some of the evidence can be taken directly from insurance reports. When ABS debuted, insurance companies said accident rates actually increased for vehicles equipped with the systems.

One of the researchers gave a good example of the offset hypotheses theory in a report from Wards Auto. He noted that when he drives his vintage MG roadster, he doesn't tailgate or accelerate quickly on wet roads because the car doesn't have ABS or airbags. The car makers commented that the sample size of 1,307 drivers involved in 614 accidents was too small, the results unconvincing and that the findings are contradictory to their own.