Experiments show that drivers react more slowly when indicator lights are positioned nearer the centre of the car, rather than when they are fitted close to the outside edges of the body.
Experts say the reaction delay could cost other road users vital seconds when assessing which way the indicating car is going to turn.
Trials with student drivers showed they responded fastest to indicator lights that are closest to the car's front corners, as seen on the Nissan Micra used as an example in the test.
But clusters with 'inside' indicators - such as those seen on the old-shape Ford Mondeo - leave other drivers guessing for a vital moment or two longer. Worryingly, scientists reckon the effect could be even greater for older people or parents with young children in the car, as these 'real world' drivers face more distractions than the students did in the trials.
Experiments were carried out in a laboratory, where volunteers were shown pictures of the front of cars - one a basic diagram, the other real - and had to push buttons as an indicator lit. "The study shows that in-board lamps could reduce safety," claimed Dr Andrew Bayliss at the University of Wales, Bangor.
"Designers want to create good-looking cars, but this focus on styling should not come at the expense of safety. The position of lights on the vehicle should be guided by protection, not aesthetics."
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