The current investigation was conducted to elucidate whether errors of commission in the Sustained Attention to Response Task are indicators of perceptual or motor decoupling. Twenty-eight participants completed SARTs with motor and perceptual aspects of the task manipulated. The participants completed four different SART blocks whereby stimuli location uncertainty and stimuli acquisition were manipulated. In previous studies of more traditional sustained attention tasks stimuli location uncertainty reduces sustained attention performance. In the case of the SART the motor manipulation , but (...) not the perceptual manipulation significantly reduced commission errors. The results suggest that the majority of SART commission errors are likely to be indicators of motor decoupling not necessarily perceptual decoupling. (shrink)