This study investigated the ability of Zen meditators and non-meditators to sustain attention during an ongoing task. We hypothesized that meditators (n = 15) would sustain attention more efficiently than non-meditators (n = 19) by responding faster to task stimuli, making fewer commission errors, and reporting fewer interfering thoughts in the sustained attention to response task (SART). Their motivation to do the SART was evaluated with the motivation scale of the Dundee Stress State Questionnaire (DSSQ), and after participants had completed the SART, they reported whether they had experienced task-related and task-irrelevant interferences through the thinking content scale of the DSSQ. The results indicated that meditators had higher intrinsic motivation (although this scale had very low reliability) towards the SART whereas non-meditators had higher success motivation. Meditators and non-meditators did not significantly differ on commission errors on the SART, but meditators responded faster to SART stimuli. Meditators reported fewer task-related interferences than non-meditators, but the groups did not differ in the amount of task-irrelevant interferences. These results suggest that the difference between meditators and non-meditators is more nuanced than just a generalized improvement of the former in sustained attention.