People frequently underestimate the time needed to complete tasks and we examined a strategy – known as backward planning – that may counteract this optimistic bias. Backward planning involves starting a plan at the end goal and then working through required steps in reverse-chronological order, and is commonly advocated by practitioners as a tool for developing realistic plans and projections. We conducted four experiments to test effects on completion time predictions and related cognitive processes. Participants planned for a task in one of three directions (backward, forward, or unspecified) and predicted when it would be finished. As hypothesized, predicted completion times were longer (Studies 1–4) and thus less biased (Study 4) in the backward condition than in the forward and unspecified conditions. Process measures suggested that backward planning may increase attention to situational factors that delay progress (e.g., obstacles, interruptions, competing demands), elicit novel planning insights, and alter the conceptualization of time.
