Editing Sunk cost (section)

=== Overoptimistic probability bias ===

In 1968, Knox and Inkster<ref>{{Cite journal | doi = 10.1037/h0025528 | last1 = Knox | first1 =  RE| last2 = Inkster | first2 =  JA| year = 1968 | title = Postdecision dissonance at post time | journal = Journal of Personality and Social Psychology | volume = 8 | issue = 4| pages = 319–323 | pmid = 5645589 }}</ref> approached 141 [[Betting on horse racing|horse bettors]]: 72 of the people had just finished placing a $2.00 bet within the past 30 seconds, and 69 people were about to place a $2.00 bet in the next 30 seconds. Their hypothesis was that people who had just committed themselves to a course of action (betting $2.00) would reduce post-decision dissonance by believing more strongly than ever that they had picked a winner. Knox and Inkster asked the bettors to rate their horse's chances of winning on a 7-point scale. What they found was that people who were about to place a bet rated the chance that their horse would win at an average of 3.48 which corresponded to a "fair chance of winning" whereas people who had just finished betting gave an average rating of 4.81 which corresponded to a "good chance of winning". Their hypothesis was confirmed: after making a $2.00 commitment, people became more confident their bet would pay off. Knox and Inkster performed an ancillary test on the patrons of the horses themselves and managed (after normalization) to repeat their finding almost identically. Other researchers have also found evidence of inflated probability estimations.<ref name="Arkes and Blumer">{{Cite journal | doi = 10.1016/0749-5978(85)90049-4 | last1 = Arkes | first1 = Hal | last2 = Blumer | first2 = Catherine | year = 1985 | title = The Psychology of Sunk Cost | journal = Organizational Behavior and Human Decision Processes | volume = 35 | pages = 124–140 }}</ref><ref>{{Cite journal | doi = 10.1002/1099-0771(200007/09)13:3<295::AID-BDM353>3.0.CO;2-6 | last1 = Arkes | first1 = Hal | last2 = Hutzel | first2 = Laura | year = 2000 | title = The Role of Probability of Success Estimates in the Sunk Cost Effect | journal = Journal of Behavioral Decision Making | volume = 13 | issue = 3| pages = 295–306 }}</ref>