Which type of nystagmus is influenced by watching contrasting moving objects?

Optokinetic nystagmus is characterized by eye movements that occur in response to viewing moving objects in the peripheral vision. When a person watches objects moving in a contrasting manner—such as a train moving past a stationary observer—the eyes exhibit a smooth pursuit followed by a quick eye movement in the opposite direction, resulting in the characteristic nystagmus. This type of nystagmus is significant in assessing how the visual system processes motion and can be used in various evaluations, including field sobriety tests.

The other types of nystagmus mentioned do not primarily involve the effect of viewing contrasting moving objects. Horizontal gaze nystagmus is tested during sobriety evaluations when an individual follows a stimulus horizontally. Post rotational nystagmus occurs after the head is spun and is related to balance and vestibular function rather than visual contrast. Caloric nystagmus is induced through temperature changes in the inner ear and is not linked to watching moving objects. Thus, optokinetic nystagmus is the appropriate choice given its direct relationship to visual motion stimulation.