Why Do People Increase Effort Near a Deadline? An Opportunity-Cost Model of Goal Gradients

People tend to gradually reduce effort when performing lengthy tasks, experiencing physical or mental fatigue. Yet, they often increase their effort near deadlines. How can both phenomena co-occur? If fatigue causes the level of effort to decline, why does effort rise again near a deadline? The present article proposes a model to explain this pattern of behavior and tests three predictions that follow from it. Four lab experiments (N = 311) show that effort, indexed by the rate of keypresses in a computer game, increases more steeply (a) toward a deadline than toward a performance criterion, (b) when a concurrent task is present (vs. absent), and (c) with more (vs. less) effective actions. We suggest that changes in opportunity–cost, which is the cost of missing out on alternatives when engaging in a focal action, can explain these effects. Specifically, we suggest that as the deadline approaches, (a) the value of performing competing, alternative activities decreases because they can be postponed past the deadline with lower cost, and (b) engaging in competing alternatives becomes increasingly more costly, because compensating for the lost time becomes more difficult. Both processes contribute to diminishing the net value of alternative activities and thus reduce the opportunity cost associated with engaging in the focal activity. We discuss the practical implications of this model for diverse fields such as economic behavior, sports, and education.