Mobile Phone Use

It has been estimated that around 10 to 30% of car accidents have come about following a distraction. It is not clear what proportion of these distractions is down to mobile phone use, mainly because of the legal implications of admitting using a phone when driving. But there is absolutely no doubt using a mobile phone when driving will almost always increase your risk when driving.

If you have not done so already, please read our section on schemas. A schema is a mapped process which we learn to enable us to do a task time and again (like turning at a junction, or using your phone).

Your Contention Scheduling Process is at work in routine situations when more than one schema is working (like driving and using a phone). However, should a situation arise like a car appearing on a slip road which requires you to slow or quickly change lanes, basically anything complex, your Supervisory Attentional System will automatically re-prioritise and put driving as the number one task. Both the Contention Scheduling Process and Supervisory Attentional System are excellent ways to organise and modulate what you do. However, lack of attention can cause the systems to overload. If you are engaged in a very deep conversation, you may not be able to respond (as in see) a serious hazard which should take ultimate priority.

So, we have established that using a mobile phone can be very dangerous because it can overload the Supervisory Attentional System. However, what if the system is not overloaded, is using a mobile phone still dangerous?

The answer to this is yes and no! Dual task performance such as using a mobile phone and driving a car is affected by three aspects:

  1. The mode of information input (i.e. auditory, visual, tactile)
  2. The way in which we the information is coded (i.e. either spatially or verbal)
  3. The type of response required; (i.e. manual or vocal)

If two tasks are similar in terms of their sensory or motor requirements, then interference is more likely to occur, and performance will be impaired, such as two lots of visual inputs to process. However, lets look at the processing aspects of driving and then using a mobile phone:


  1. Mode of information input = visual
  2. The way the information is coded = spatially
  3. The type of response required = manual (as in steering, braking etc)

Mobile Phone:

  1. Mode of information input = auditory
  2. The way the information is coded = verbal
  3. The type of response required = vocal

So we can see here that driving and using a mobile phone has both very different processing components. This in isolation this means that driving and using a mobile phone can be done with relative ease, as they are not using conflicting resources.

However, this is where things get complex. We have said that the mode of information input in mobile phone use is auditory. This is true, but what happens if the person on the other end of the phone is asking where you put that important file they need? You would be directing them to wherever the file is by giving instruction:

I think the file is in the second draw down by the side of the printer in Johns office, if it is not there it could be by the, etc….

As you give these instructions, you are engaging the visual mode of your thinking, as you will be picturing the location in your mind as you speak. Due to this fact your visual resources used for observing and driving become compromised.

So we can conclude that in a world where driving is very simple, such as doing 60mph on the slow lane of a motorway, which is totally empty, and conversations are always very short and basic using a mobile phone is in theory, relatively safe. However, this is very rarely the case and the way we communicate on our mobile phones often overload resources we are using to drive a car (the visual element).

Because of this we recommend never using a phone in the car, not even on hands free. Although your hands may be free, your mental resources are far too easily overloaded. While we say a short, simple conversation on a phone when driving in undemanding circumstances may not be classified as risky, it is illegal and should be avoided. Using your mobile phone also reduces your reaction times. A recent study shows this can drop from 0.95 seconds to 1.3 seconds.

Learn more about psychology of driving