在過往的實驗研究中，大部分受試者會最大化自己贏得彩卷的機率。學者以對機會公平的偏好微弱來解釋此結果。羅斯(Rawls, 1971/1999)提出另一種心理上的解釋：他認為根據隨機的結果來分配所得是不公平的。被如此不公平對待時，人們會對可能的彩卷贏家產生「有理由的忌妒」，因此會最大化自己的機率。本研究以實驗方法驗證人們是否懷有「有理由的自私」。實驗結果證實了羅斯的想法，因為大部分受試者不追求公平的預期報酬、違背了自己原本的社會偏好。此研究除了解釋為何人們最大化自身贏得彩卷機率的心理，也對公平機率是一種機會上的平等概念提出質疑。

Most subjects maximized own chances to win a lottery in previous experi¬mental studies. Scholars have explained the result by a weak concern for ex ante equality. Rawls (1971/1999) provides a psychological motive for the weak preference. He argues that distributing income according to the outcome of a lottery is “arbitrary” and unfair. Moreover, he believes that treated by the unjust institution, people could possess “excusable envy” towards potential winners, which leads them to deal with others unfairly by maximizing own chances. This study tests experimentally whether subjects practice excusable selfishness. Our results support Rawlsian thought, since many exhibited a weak preference for an equal expected payoff and deviated their baseline social preferences. The finding provides the first psychological explanation for why most people maxi-mize their winning probabilities and casts doubts on the equally lucky view of equality of opportunity.