On 1st March, tougher penalties for hand-held phone use whilst driving came into force. Those who are caught now face a £200 fine and 6 points on their licence. On announcing the change in legislation, Transport minister, Chris Grayling claimed that drivers must “take responsibility” for their actions, making phone use behind the wheel as socially taboo as drink and drug driving. This is a message few would disagree with, yet the legislation it relates to misses one crucial point: hands-free phone use is just as distracting as hand-held conversations.
The difficultly with this issue is that people are often unwilling to believe that hands-free phone use is any different from talking to a passenger. I’m often asked if this research means drivers must travel in total silence to avoid distraction, or whether I’ve ever tried to drive with screaming kids in the back of the car – surely that’s more distracting than a simple phone call? Of course, any type of secondary task whilst driving can be distracting, but phone use seems to be qualitatively different due to where both conversation partners are: someone on the phone cannot see what the driver can, and therefore consistently demands their attention. A passenger, on the other hand, can see when the driver is facing a challenging situation and can stop talking, thus reducing the amount of information the driver needs to process.
Our research takes this a step further by investigating which aspects of a phone conversation affect driving. As we all have a limited amount of mental resources available to us when completing any task, speaking on the phone introduces competition between the two tasks for these resources: the cognitive resources needed for driving may also be needed for a phone conversation. When talking on the phone, drivers may create mental images of what the other person is saying, where they are and what they’re doing. If this is the case, the conversation could have a ‘visual’ element to it, meaning some of the resources needed for accurate visual attention whilst driving may already be in use for a phone conversation.
Using a hazard detection test, we measured driver’s reaction times to hazards and their eye movements. Some drivers were distracted by a phone task which sparked their visual imagination, and others completed a phone task which did not require imagery. A final group of drivers completed the task without any distraction. Unsurprisingly, we found that dual tasking drivers reacted to fewer hazards, and took longer to react to those hazards they did notice, than undistracted drivers. But, those who were distracted by a conversation sparking mental imagery were the most distracted. Of more interest to us was the finding that those distracted by imagery took longer than undistracted drivers to react to hazards that occurred right in front of them, in the centre of the driving scene, yet did not take longer to react to hazards in the periphery – to the sides - of the scene. This seemed odd, until we established a worrying trend: very few dual tasking drivers reacted to the peripheral hazards at all, suggesting they hadn’t seen them.
Eye-tracking data revealed that dual tasking drivers looked at an area of the driving scene around four times smaller than undistracted drivers – in fact, they tended to focus on a small area at the centre of the scene, largely ignoring what was happening at either side. But, even though they were looking directly ahead, dual taskers took longer to react to hazards presented at that point, and on occasion still missed them altogether!
Taking hazard detection and eye-tracking data together we were able to identify that dual tasking drivers can look at a hazard yet fail to see it, due to a lack of available cognitive resources.
So, having two hands on the wheel and two eyes on the road isn’t enough if a driver is distracted by a phone call. Essentially, distracted drivers can be ‘cognitively blind’ to important aspects of the driving scene, making them more likely to be involved in accidents which could affect both their own and others’ safety. Phone use behind the wheel should definitely be as socially unacceptable as drink driving, but legislation needs to recognise and acknowledge decades of scientific research which emphatically demonstrates that hands-free phone conversations pose a significant danger.
Dr. Gemma Briggs
The Open University