The quiet eye effect describes the performance advantage associated with a long ocular fixation on a critical target of an action, prior to and during movement execution. Researchers have advocated a multimeasure approach to shed light on the mechanism(s) behind the association between ocular activity and motor performance. In this study we used psychophysiological methods to test whether the quiet eye period is associated with enhanced visual processing (visual hypothesis) or longer movement durations (postural-kinematic hypothesis). Thirty two recreational golfers putted 20 balls to a 2-m distant target on a flat surface. We examined quiet eye duration and time-varying eye quietness using electrooculography, occipital alpha power using electroencephalography, and swing duration using kinematic sensors. Occipital alpha power, an inverse neural marker of visual processing, increased prior to and during swing execution, suggesting decreased visual processing compared with baseline. Correlations revealed that, despite the overall decrease, visual processing decreased less with a longer quiet eye and greater eye quietness. Importantly, swing duration was strongly and positively correlated with both indices of ocular activity: longer quiet eye and greater eye quietness were associated with longer swing duration. Our findings support the postural-kinematic hypothesis, confirming that the duration of the quiet eye is associated with a slow movement execution, and question the role of visual processing in the final moments of closed-loop aiming tasks. We anticipate major advancements in the mechanistic understanding of the quiet eye effect as researchers adopt psychophysiological methods to examine eye movements in combination with measures of other biological systems.