Acetylcholine acts as a neuromodulator in the central nervous system as it plays an important role in the control of motor and cognitive functions. However, little is known about how motor control and cognition is affected by targeted pharmacological interventions that alter central cholinergic neurotransmission. As such, this Thesis investigated the effects of over-the-counter medications with varying degrees of central anticholinergic activity on oculomotor function (smooth pursuit and saccadic eye movement), ocular responses (pupil diameter and blink rate) and cognition (attention network test) in healthy young adults. All experiments were double-blind, placebo controlled, human, four-way cross-over trials. Physiological responses were obtained from each subject pre-ingestion as well as 0.5 h and 2 h post-ingestion of promethazine hydrochloride (strong centrally acting anticholinergic), hyoscine hydrobromide (moderate centrally acting anticholinergic), hyoscine butylbromide (anticholinergic devoid of central properties), and a placebo.