Classical prospect theory assumes different prospects are generated by comparing to the reference point and the default reference point is the status quo. Current decision neuroscience research mainly focuses on the prospects of gains and losses concerning the status quo and has made tremendous advances in the understanding of the underlying neural mechanisms involved in these processes. Here we investigate how human subjects make economic decision under risk, especially after they endure monetary losses in the first place. Contrary to the standard escalation effect of commitment, subjects tended to be less inclined to commit to the risky gamble. However, if the previous loss was “written off” by unexpected windfall, then the de-escalation effect disappeared. We propose the involvement of mental accounting cognitive process and the potential neural computations implicated.