What function is primarily affected by fatigue in drivers?

Fatigue significantly impacts cognitive functions, particularly decision-making and reaction time in drivers. When a driver is fatigued, their brain may not process information as quickly or accurately as it normally would. This delay in cognitive processing can result in slower reaction times to hazards, difficulty in making safe driving decisions, and impaired judgment regarding speed and distance.

For example, a fatigued driver may take longer to recognize a stopped vehicle ahead or might fail to assess the appropriate response to changing traffic conditions. This is crucial because quicker decision-making is often necessary in dynamic driving environments to ensure safety. While other functions such as vision and coordination can also be impaired by fatigue, the core issues revolve around how quickly a driver can react to their environment and make appropriate decisions, which are directly tied to cognitive functioning.