What factor causes a decrease in a vehicle drivers's field of vision?

The main factor that causes a reduction (narrowing) of the driver's field of vision is an increase in speed. This phenomenon is called 'tunnel vision' – the faster we go, the more our attention focuses on what is far ahead of us, and objects on the periphery of our vision become unnoticeable. For this reason, at high speed, it is easy to miss, for example, a pedestrian stepping onto the road or an animal running out of a forest.