What occurs when a driver displays a lack of smooth pursuit?

When a driver displays a lack of smooth pursuit, it indicates that the eyes are unable to smoothly track a moving object, and instead, they exhibit jerky or discontinuous movements. This is often observed in individuals who may be impaired, as their ability to visually follow a moving stimulus—like an officer's finger during a field sobriety test—is compromised.

Smooth pursuit is a critical function of the visual system, allowing for stable and continuous tracking of moving objects. A lack of smooth pursuit can be a sign of impairment, as typically, our eyes should move fluidly to maintain focus without jerking. The jerking motion reflects cognitive deficits or motor control issues often associated with alcohol or drug impairment.

The other answer choices describe different situations that do not demonstrate lack of smooth pursuit, such as remaining still while tracking or moving too quickly, neither of which denote the lack of smooth eye coordination seen in distracted or impaired drivers.