Satnav systems sometimes send motorists the wrong way and they can also impair their driving ability, according to a UK study.
Drivers' performance was affected when listening to satnav-style directions in an experiment carried out by Lancaster University and Royal Holloway, University of London.
A computer set volunteers tasks which mimicked the instructions issued by a satnav.
The results showed that when people were following complicated satnav instructions they tended to drive faster, with more steering variations, as well as being less likely to notice pedestrians who may be stepping out.
Dr Polly Dalton, from the Department of Psychology at Royal Holloway, says, "What is interesting is that people were able to follow one simple instruction without any significant impact on their driving.