Visual Cues

The human visual system receives the information that helps us figure out which is the closest or farthest object from us. These cues originate partly in the world around us, and partly within our eyes. Sometimes a doubt arises as to our ability to accurately perceive what is closer or farther and then to respond correctly.

Reacting to Obstacles

In the context of driving, some collisions occur as a result of errors made about objects in our environment. While driving, we very often encounter various road problems. When faced with problems, we must be able to evaluate them and their distance from us. We must then react to it in time; that is, before we collide with them. This point raises one of the fundamental components of driving, i.e. the drivers' ability to predict events that are about to take place within a short period of time, and their ability to react to them in the best way possible.

Predicting Events

Drivers must estimate just how close they are to a collision, so as to turn the steering wheel in time. Estimation of the time it will take to reach the problem and the driver's ability to act accordingly, are considered two of the principle skills required for driving control. Estimation can involve stationary objects located at the side of the road that require the driver to react. A considerable number of crashes occur when stationary or slow-moving vehicles are the road obstacles. This issue is relevant not only when a problem stands in the driver's way, but also when over - taking or crossing lanes, situations in which drivers must determine whether they have enough time to execute and complete the manoeuvre.

What Helps Predicting Events?

Researchers have found the (mental) evaluation of an expected collision is influenced by two types of environments. First, when the driving environment is relatively calm, the driver tends to over-estimate how much time he/she has before the collision will occur. The collision seems farther away than it really is, and so the driver will probably start responding to the problem later than is required, which might be too late. Second, when the environment is abundant in details. In this case, collisions are perceived to be closer in time, so the reaction to them takes place earlier.

Travel Speed As a Predictor

Another evaluation factor is how fast you are travelling. In general, when driving faster, you tend to believe you are farther away from a collision than you really are. The less demanding the drive, the greater the error in judging how much time you have and therefore the driver tends to make mistakes like braking late. This relates to the speed in which information is processed by the brain; at high speeds with little going on around you the brain does not receive sufficient information, or does not have enough time to process what information you gather up optimally. People vary in the degree to which they accurately estimate distance, depth and time to collision, and these differences are shown in differences in driving and road performance.

Based on:
Cavallo V., Mestre D., Berthelon C. (1997). Time to collision judgments: Visual and spatio - temporal factors. In Rothengatter, T & Vaya, E.C. (Eds), Traffic and Transport Psychology (pp.97 - 111). U.K: Pergamon.