Crowded roads, combined with a growing number of visual, audio and other stimuli vying for our attention, have pushed driver distraction to the top of a lengthy list of traffic-safety problems.

Driving is a mental and visual exercise. Our eyes gather information and pass it to the brain for interpretation. Based on a number of factors, principal among them experience, the brain separates the inconsequential details from those pertinent to driving. As issues arise requiring driver input, the brain sends a message to the appropriate nerves and muscles and we turn the wheel, apply the brakes, etc.

The eyes may well see something of importance, but if the brain is occupied elsewhere, the information passed on goes nowhere.

Driver distraction is a perfect example of this. When our eyes or brain are occupied with something other than the task at hand, we are in effect not driving.

While in-car cellphone-use gets all the attention, it is only the latest and most obvious form of driver distraction. It's not the cellphone per se, but the conversation where the true problem lies, as it occupies the participant's mind.

Similarly, we may be distracted by conversations with other occupants in the vehicle, the level of distraction growing in proportion to the depth of the conversation.

Studies have determined stages of when additional input puts the driver into overload. For example, a cellphone ringing while a driver is on the entrance ramp to the freeway, passing on a two-lane road or changing lanes in heavy traffic is much more distracting than if it rang while driving at a leisurely pace down an empty country road.

Wireless communication and in-vehicle entertainment systems are the most recent contributors to the problem.

In the 1960s, it was the car radio; the tape player came along in the '70s; the CD player in the '80s. By the turn of the century, they had been joined by the cellphone, trip computers and navigation systems, MP3 players, video/DVD entertainment systems and Internet access.

But there is a great deal more than electronics at play here.

A study conducted in Washington, D.C., revealed eating to be the most common form of distraction in that city, with 65 per cent of drivers admitting to eating while driving and 58 per cent to talking on their cellphones.

Twenty-five per cent of the 600 respondents said they applied makeup while driving.

Closer to home, a study by researchers at Memorial University in Newfoundland validated what parents have known all along -- loud noise slows reaction time and affects decision-making abilities.

There is no question, roads and drivers would be safer with fewer distractions. But distractions are a reality. How we deal with them is the issue.

Halifax-based Richard Russell

runs a driving school