Wronging past rights: The sunk cost bias distorts moral judgment

Wronging past rights: The sunk cost bias distorts moral judgment. Ethan A. Meyers et al. Judgment and Decision Making, Vol. 14, No. 6, November 2019, pp. 721-727. http://journal.sjdm.org/19/190909b/jdm190909b.html

When people have invested resources into an endeavor, they typically persist in it, even when it becomes obvious that it will fail. Here we show this bias extends to people’s moral decision-making. Across two preregistered experiments (N = 1592) we show that people are more willing to proceed with a futile, immoral action when costs have been sunk (Experiment 1A and 1B). Moreover, we show that sunk costs distort people’s perception of morality by increasing how acceptable they find actions that have received past investment (Experiment 2). We find these results in contexts where continuing would lead to no obvious benefit and only further harm. We also find initial evidence that the bias has a larger impact on judgment in immoral compared to non-moral contexts. Our findings illustrate a novel way that the past can affect moral judgment. Implications for rational moral judgment and models of moral cognition are discussed.

Keywords: sunk costs, morality, decision-making, judgment, open data, open materials, preregistered

4  General Discussion

We found that the sunk cost bias extends to moral judgments. When costs were sunk, participants were more willing to proceed with a futile, immoral action compared to when costs were not sunk. For example, they were more willing to sacrifice monkeys to develop a medical cure when some monkeys had already been sacrificed than when none had been. Moreover, people judged these actions as more acceptable when costs were sunk. Importantly, these effects occurred even though the benefit of the proposed immoral action was eliminated.
Our findings illustrate a novel way that the past can impact moral judgment. Moral research conducted to-date has focused extensively on future consequences (e.g., Baez et al., 2017; Miller & Cushman, 2013). Although this makes normative sense as only the future should be relevant to decisions, it is well known that choice is affected by irrelevant factors like past investment (Kahneman, 2011; Kahneman, Slovic & Tversky, 1982; Szaszi, Palinkas, Palfi, Szollosi & Aczel, 2018; Tversky & Kahneman, 1974). As such, our findings show that as is true with other (non-moral) judgments, people’s moral judgments are affected by factors that rational agents “should” ignore when making them.
Further, our findings show that a major decision bias (i.e., the sunk cost effect) extends to moral judgment. This finding is broadly consistent with research showing that moral judgments are affected by such biases. This earlier work shows that when making moral judgments, people are sensitive to how options are framed (e.g., Shenhav & Greene, 2010) and prefer acts of omission over commission (e.g., Bostyn & Roets, 2016). For example, people make different moral judgments when the decision is presented in a gain frame than when it is presented in a loss frame, even though these two decisions are logically identical (Kern & Chugh, 2009). Likewise, people judge lying to the police about who is at fault in a car accident (a harmful commission), to be more immoral than not informing the police precisely who is at fault (a harmful omission) (Spranca, Minsk & Baron, 1991). However, unlike most of these previous demonstrations, our findings directly compare the presence of decision-making biases across moral and non-moral contexts (also see Cushman & Young, 2011).
In our first experiment, we also found that the sunk cost bias may be stronger in moral decision-making than in other situations. This is surprising. In non-moral cases proceeding with a futile course of action is wasteful. But in our moral version of the scenarios, proceeding is wasteful, harmful to others, and morally wrong. Yet, there was a greater discrepancy between willingness to act in response to sunk costs in the immoral condition. Increasing the reasons to not proceed with the action amplified the sunk cost bias. One potential explanation for this is that people are unwilling to admit their prior investments were in vain (Brockner, 1992). People succumb to the sunk cost bias in part because they feel a need to justify their past decisions as correct (Ku, 2008; also see Staw, 1976). Likewise, moral judgments seem to generate a much greater need to provide reasons to justify past decisions (Haidt, 2012). Thus, those making decisions in an immoral context might have additional pressures to justify their previous choice that stem from the nature of moral judgment itself.
Another explanation is that the initial investment was of a larger magnitude in the immoral compared to the non-moral condition. In both cases, participants incurred an economic cost, but only in one did participants incur an additional moral cost. People are more likely to succumb to the sunk cost bias when initial investments are large (Arkes & Ayton, 1999; Arkes & Blumer, 1985; Sweis et al., 2018). Perhaps sunk costs exerted a greater effect in the immoral condition because the past investments were greater (i.e., of two kinds: economic and moral, rather than just one: economic). However, as we do not know if the economic resources (e.g., pine trees and lab monkeys) were of comparable value, the discrepancy between moral conditions may entirely stem from the lab monkeys being valued higher and thus larger in investment magnitude. Thus, we are hesitant to draw any strong conclusion from this finding. The difference in sunk cost magnitude could stem from differences in financial costs between the immoral and non-moral contexts.
Our finding that moral violations led to increased willingness to act is reminiscent of the “what the hell” effect, in which people who violate their diet then give up on it and continue to overindulge (Cochran & Tesser, 1996; Polivy, Herman & Deo, 2010). We see this as similar to persisting in an immoral course of action after costs have been sunk. After engaging in a morally equivocal act, people may feel disinhibited and willing to continue the act even when its immorality becomes clear. Likewise, people may persist in an attempt to maintain the status quo (Kahneman, Knetsch & Thaler, 1991; Samuelson & Zeckhauser, 1988). These accounts, though, may not explain why sunk costs changed people’s moral perceptions. One possibility is that this resulted from cognitive dissonance between people’s actions and their moral code (Aronson, 1969; Festinger, 1957; Harmon-Jones & Mills, 1999). For example, sacrificing monkeys to develop a cure may cause dissonance between not wanting to harm but having done so. To resolve this, people might change their moral perceptions, molding their moral code to fit their behavior.
We close by considering a broader implication of this work. The extension of decision biases to moral judgment has been previously construed as supporting domain-general accounts of morality that suggest moral judgment operates similarly to ordinary judgment (Osman & Wiegmann, 2017; Greene, 2015). This is because if morality is not unique, one could reasonably expect that a factor that affects ordinary judgment would likewise affect moral judgment. Thus, if information irrelevant to the decision at hand (e.g., past investments) influences whether we continue to bulldoze land to build a highway, so too should it influence the same bulldoze decision that requires confiscating the land. This is not conclusive however, and our findings could be interpreted to support domain-specific accounts instead (e.g., Mikhail, 2011). For instance, the sunk cost bias was demonstrably larger in moral judgments. Nevertheless, an interpretation of our results as evidence for a domain-general account of morality must explain how the varying effect of past investment on judgment is a difference in degree but not kind.