Dozens of subsequent studies have established that prospective timing is strongly modulated by cognitive load: the more complex or challenging a task, the shorter the estimates of how much time was spent performing the task (53 versus 31 seconds). The opposite can happen with retrospective timing: the higher the cognitive load, the longer the task can seem (28 versus 33 seconds). Retrospective timing, however, is not as strongly modulated by cognitive load as prospective timing.8
