Sustaining focus is difficult, but it is under our control.Previous research has found that people’s ability to sustainattention depends on external incentives and changes overthe lifespan. However, previous research has made limitedprogress in characterizing the specific cognitive mechanismsinvolved in sustained attention. These mechanisms areinvestigated in the current experiment, which uses driftdiffusion modeling to re-analyze a series experiments onsustained attention. In Experiment 1, we found that incentivesinfluence information processing (noise) but not decisionstrategy (threshold). In Experiment 2, we found that noiseand threshold have distinct development trajectories, andthat while older adults have noisier accumulation, they arebetter at sustaining attention. These results help providemechanistic insight into recent findings in sustained attention.