- Neural activity during repeated presentations of a sensory stimulus exhibits considerable trial-by-trial variability. Previous studies have reported that trial-by-trial neural variability is reduced (quenched) by the presentation of a stimulus. However, the functional significance and behavioral relevance of variability quenching, and the potential physiological mechanisms that may drive it have rarely been studied. Here we recorded neural activity with EEG as subjects performed a two-interval forced-choice contrast discrimination task. Trial-by-trial neural variability was quenched by approximately 40% after the presentation of the stimulus, relative to the variability apparent before stimulus presentation, yet there were large differences in the magnitude of variability quenching across subjects. Individual magnitudes of quenching predicted individual discrimination capabilities such that subjects who exhibited larger quenching had smaller contrast discrimination thresholds and steeper psychometric function slopes. Furthermore, the magnitude of variability quenching was strongly correlated with a reduction in broadband EEG power after stimulus presentation. Taken together, our results suggest that neural variability quenching is achieved by reducing the amplitude of broadband neural oscillations following sensory input, which yields relatively more reproducible cortical activity across trials, and enables superior perceptual abilities in individuals who quench more. Significance Statement Variability quenching is a phenomenon whereby neural variability across trials is reduced by the presentation of a stimulus. While this phenomenon has been reported across a variety of animal and human studies, its functional significance and behavioural relevance has rarely been examined. Here we report novel empirical evidence from humans which reveals that variability quenching differs dramatically across individual subjects and explains, to a certain degree, why some individuals exhibit better perceptual abilities than others. In addition, we found a strong relationship between variability quenching and suppression of broadband neural oscillations. Taken together, our results reveal the importance of reproducible cortical activity for enabling better perceptual abilities and suggest a potential underlying mechanism that may explain why variability quenching occurs.