Research has revealed that motorists who use sat nav systems are less aware of potential hazards in the road.
A study of 70 adults at Anglia Ruskin University in Cambridge found that drivers who focus their eyes on one pattern of information, such as a map or line of text, then struggle to readjust their eyes when they look back at the road.
In the study, men and women were shown street scenes and asked to identify potential hazards. Some were shown a line of letters and asked to count the vowels prior to viewing the street scene and unsurprisingly, it was this latter group who were slower to spot the dangers.
Psychologist Michael Pake, who carried out the research, claimed that the motorists' inability to spot hazards was due to a 'carryover effect'.
The carryover effect is caused when people switch from a repetitive task, such as scanning letters, to something much more random, for example looking for hazards on a busy road.
The person in question may face difficulty when it comes to switching between these mindsets, and as a result could miss spotting the dangers.
Commenting on the study's findings, Dr Pake said: 'Our research shows that an individual's immediate attention can be affected by previous tasks.
'In driving settings, this could impact on the safety of road users as reading information on a sat-nav, or even road signs, could cause a change in scanning behaviour and increase the risk of a hazard being missed.
'Further research should be carried out to explore the full extent of this effect and examine to what degree this 'carry over' influences road safety.'