The brain

To drive safely, you must constantly perceive, interpret and process what is happening around you. This is handled by the brain with the help of your senses.

You are aware of your surroundings because the brain constantly works to analyse and process all the information your senses provide. In order for you to be able to pay attention to the right things, rather than all things, the brain selects the most important impressions.

The brain selects the impressions that are most important to pay attention to and filters out those less important

The brain can only handle a limited amount of information at a time. If many things happen at once, the risk of missing important information increases.

The brain is also influenced by what you expect to happen. This can cause you to overlook things that deviate from the normal, such as a child running out into the road or a vehicle stopped in an unexpected place.

When you are starting out as a driver your brain has not yet learned which impressions are the most important. This means that you sometimes might pay attention to the wrong things, make wrong assessments or make incorrect decisions.

Scanning

How you use your vision while driving affects how much information you are able to take in and process.

Inexperienced drivers usually have a short and narrow field of observation. They also tend to fix their gaze on static objects such as the roadside, the central barrier or parked cars.

Experienced drivers usually have a longer and broader field of observation. They are also better at paying attention to moving objects without fixing their eyes on an object longer than is necessary.

By scanning further ahead and more widely, you give yourself more time to detect, understand and deal with risks

Experienced drivers are often able to perceive, sort and prioritise information – both consciously and subconsciously – much faster than new, inexperienced drivers can. When you are new in traffic, it is important to stay active, move your gaze, and look far ahead. You should also avoid fixating on one object for longer than necessary.

Whether you are a new or an experienced driver, your field of observation becomes narrower at high speeds. This phenomenon is called tunnel vision. For this reason, it is especially important to keep scanning actively when driving at higher speeds.

The higher your speed, the less time the brain has to perceive, interpret and react to what is happening in traffic.

Remember: Keep your eyes moving and look well ahead.

Reaction ability

When something unexpected happens in traffic, it is important that you quickly notice it and react in the right way, for example by veering or braking.

It is your brain that determines how quickly you react. The time it takes is called reaction time and is determined by your reaction ability – the better your reaction ability, the shorter your reaction time. Reaction time varies between individuals and situations, but is on average approximately 1 second.

Reaction time is the time between detecting a hazard and starting to brake or steer away

In traffic, good reaction ability is not just about how quickly your body responds. Readiness for action, risk awareness, driving style and experience also affect how quickly you can react when something happens. If you actively scan the traffic, adapt your speed and are prepared for the situation to change, you will often detect hazards earlier and be better prepared to act. This gives you more time to brake, steer away or take other action. Experience can also make it easier to recognise risky situations early and be prepared for how to respond.

Fatigue, distraction, alcohol, drugs and illness can impair your ability to react and increase your reaction time. The car will then travel further before you start braking or steering to avoid the hazard.

It is your reaction time and the car's speed that determines how long the reaction distance will be during a braking event. Reaction distance is the distance the car travels from the moment you discover an obstacle or a hazard until you apply the brakes.

Remember: The earlier you detect a hazard, the more time you have to act.

Assessment ability

Your brain is constantly working to assess all situations based on your theoretical knowledge and your practical experience. If you have never learned about braking distances or had to brake hard, it is very difficult for your brain to judge where your car will stop if you suddenly have to brake heavily.

We can judge distances to some extent, but we often find it harder to judge speed. It is particularly difficult to judge the speed of oncoming vehicles, which makes overtaking and turning left especially risky. Vehicles approaching from the side, such as a car on a crossing road, can often be easier to judge because their sideways movement is clearer.

Judging the speed of an oncoming vehicle is very difficult

Assessing the meeting point

Meetings with oncoming vehicles usually occur much earlier than we think they will. If you are going to overtake another vehicle or turn left on a country road and misjudge the distance to an oncoming vehicle, or the oncoming vehicle's speed, the consequences can be devastating.

Always expect meetings with oncoming vehicles to come earlier than you think. Do not take chances – if you feel uncertain of where a meeting will take place, it is better to wait with the overtaking manoeuvre or the left turn.

How the brain works

To judge and calculate distances and speeds, the brain uses a variety of clues and details that it interprets and analyses. For example, verge markers or street lamps along a road can help the brain estimate the distance to a particular point further away, and how quickly an oncoming car grows in size gives an indication of its speed.

If these clues and details become unclear due to darkness, rain, snow, fog or the like it will be much more difficult for the brain to make accurate assessments.

Driving in heavy snow makes it very difficult for your brain to make accurate assessments, especially if you use full beam headlights

Sometimes the brain even interprets certain impressions completely incorrectly, which in the worst case can lead to optical illusions.

Common misjudgements and optical illusions

• A car with a broken headlight can be interpreted as a motorcycle, which may cause you to misjudge the vehicle's distance or speed.
• Heavy snow and full beam headlights can make you disoriented, causing you to drive off the road.
• A curvy and hilly road can make you misinterpret a slope or misjudge a turn.
• A motorcycle can be mistaken for a moped, which can be dangerous if you, for example, enter a junction and the vehicle is travelling much faster than you expected.

A car with a broken headlight can be interpreted as a motorcycle

Alcohol, drugs and fatigue

Alcohol, drugs and fatigue significantly impair the brain's ability to make accurate assessments, which can lead to optical illusions even under normal driving conditions – for example, when driving on a straight road in daylight.

Alcohol, drugs and extreme fatigue can also lead to hallucinations. A hallucination is a perception of something that is not really there, as distinct from an optical illusion, which is a misinterpretation of something real. Hallucinations are entirely created by the brain.

Vision

Vision is your most important sense in traffic and gives the brain much of the information you need to drive safely.

Your field of vision consists of direct vision and peripheral vision. You use direct vision when you look directly at something and need to see details clearly, such as a road sign, a traffic light or another road user's signal.

Peripheral vision helps you notice things happening outside the point you are looking directly at, especially movements and changes around you. For example, it can help you spot a pedestrian approaching a pedestrian crossing, a car starting to pull out of a parking space or a cyclist emerging from a side street.

Peripheral vision can often alert you that something is happening, but to see clearly what it is, you need to look in that direction. It is therefore important to move your gaze actively and not keep looking at just one point.

Peripheral vision can be impaired by fatigue, stress, alcohol and drugs

To have a class B driving license, you must have a visual acuity of at least 0.5. If you require glasses or contact lenses to reach that level, you must use them when driving. It is important to check your vision periodically, as it deteriorates with age.

There is also a risk of developing an eye disease or visual impairment as a result of another disease. Pay attention to your vision and never drive if you notice your eyesight has suddenly deteriorated.

The effects of visual defects are most noticeable in the dark. In darkness, it becomes harder to see details and contrasts, which means impaired vision can affect your driving more than in daylight.

You must have a visual acuity of at least 0.5, using glasses or contact lenses if necessary, for a B driving license

Alcohol impairs vision

One of the many reasons why mixing alcohol and driving is dangerous is that alcohol impairs your vision. As the blood alcohol level increases, the eyes' ability to cooperate decreases. This, in turn, leads to a reduced ability to assess distances. Glare sensitivity is also increased, and peripheral and night vision is impaired. A person who is heavily intoxicated may start to see double.

In darkness, these negative effects are enhanced.

Sun glare

When you are dazzled by the sun, your vision is impaired and your brain receives less information. It is therefore important to do what you can to avoid being dazzled. For example, if you are approaching the end of a tunnel on a sunny day or can see that the sun will be directly in front of you after a bend, you should lower the sun visor and put on sunglasses before you are dazzled.

However, being dazzled always be avoided. If you are dazzled, you should reduce your speed, increase the distance to the vehicle in front and drive extra carefully, especially at junctions, roundabouts and traffic lights, and on stretches of road with oncoming traffic or unprotected road users.

In strong sunlight, you may temporarily become so dazzled that you can hardly see anything at all. If this happens, reduce your speed and stop the car as soon as it is safe to do so. Do not continue driving until your vision has returned to normal.

In the winter, the sun is lower in the sky than in the summer, which increases the risk of being dazzled

It is not only in summer that the sun can reduce your visibility. On winter afternoons, the sun may be so low in the sky that it shines directly through the windscreen. In clear weather, the glare can then seriously reduce your visibility. Make sure the windscreen is clean, as even small amounts of dirt can make the glare worse.

The other senses

Although sight is the most important sense when driving, our other senses also help us detect faults and hazards.

Hearing can make you attentive:

• When another driver honks, accelerates or brakes.
• When an emergency vehicle with its sirens on is nearby.
• When something is wrong with the car, such as a poorly tensioned alternator belt.
• When you happen to drift onto a shoulder rumble strip at the side of the road.
• When the road surface condition changes.
• When you shift to the wrong gear.

Touch and sense of balance can help you:

• Select the correct gear without having to look.
• Feel how the car handles on the road, for example if it is slippery.
• Feel if the steering wheel shakes.
• Feel the vibrations when you drive over a rumble strip at the edge of the road.

Smell can make you attentive:

• If exhaust gases enter the car.
• If there is leakage of hazardous substances or a fire further down the road.
• If the clutch is overheated (it then emits a burning smell).

Hearing, touch, balance and smell also help you drive safely and detect risks in traffic