According to the principle of energy-conservation principle, effort investment is usually reduced in situations that are perceived as uncontrollable. This is because when success is recognized as impossible, any effortful actions are no longer justified. However, we predicted that individual differences in uncertainty tolerance, i.e., the need for closure (NFC), may moderate effort investment in uncontrollable situations. We tested this prediction in two experimental studies in which we exposed participants with differing levels of NFC to uncontrollable events, and indexed effort through the assessment of systolic blood pressure (SBP) responses. As predicted, in the uncontrollability (vs. controllability) condition, effort investment decreased significantly among low- but not high-NFC participants. Since gaining certainty and achieving closure is not a critical epistemic goal for low-NFC individuals, exerting extra effort to gain certainty is therefore no longer justified. On the other hand, high-NFC participants do not withhold their efforts, as they are highly motivated to obtain certainty. These results may help to account for contradictory findings in effort-investment behaviour and add substantively to the literature concerning motivation toward closure.

根据节能原理，通常会在无法控制的情况下减少工作量投资。这是因为当成功被认为是不可能的时，任何费力的举动就不再合理。但是，我们预测不确定性容忍度方面的个体差异（即需要关闭（NFC））可能会降低无法控制情况下的精力投入。我们在两项实验研究中测试了这一预测，在这项研究中，我们将具有不同NFC水平的参与者暴露于无法控制的事件中，并通过评估收缩压（SBP）反应来索引努力。如预测的那样，在不可控制性（相对于可控制性）条件下，低NFC参与者而非高NFC参与者的努力投入显着减少。由于对于低NFC个体而言，获得确定性并实现封闭并不是重要的认识论目标，因此不再需要付出额外的努力来获得确定性。另一方面，高NFC参与者并不会因为努力获得确定性而放弃他们的努力。这些结果可能有助于解释努力投资行为中的矛盾发现，并为有关关闭动机的文献提供实质性补充。