The previous theoretical background section has illustrated that there exists a broad concep- tion of decision inertia in judgement and decision-making research. This variance makes the investigation of decision inertia and the identification of relevant work a difficult endeavour. Furthermore, decision inertia and decision inertial behaviour has previously been studied un- der various other labels. There exists a wide range of loss aversion and avoidance biases and phenomena that may have a conceptual overlap with decision inertia. As a result, there re- mains a need to further clarify the concept of decision inertia.
Decision Avoidance:The concept of decision avoidance as a general umbrella term for biases resulting in non-decisions, proposed by Anderson (2003). He reviewed studies of avoidance bi- ases and phenomena in judgement and decision-making literature, discussing possible drivers of choice deferral, inaction inertia, omission bias, and status quo bias as the driving forces behind human decision avoidance. As a result he has generalized these findings in a model of a "psychology of doing nothing", postulating that decision avoidance is caused in particular by anticipated regret, and selection difficulty (Anderson, 2003). Although, this finding might be useful in explaining and investigating other decision biases, it remains open whether this assumptions hold for decision inertia. He supposed relations of the drivers have been derived from a literature review, and they lack an experimental validation. Alison is more clear, posit- ing that decision inertia "is distinct from decision avoidance (Anderson, 2003) where decision- makers refuse to evaluate choice through passive inaction (e.g., ‘I choose not to decide for the time being’). Instead, I have observed how decision-makers fail to act through ‘decision inertia’" (Alison et al., 2015).
Status Quo and Omission Bias:One of the most common biases related to decision inertia, is the status quo bias (and its sub-aspect omission bias (Ritov & Baron, 1992)). The status quo bias is based on the assumption that a "decision maker in the real world may have a consid- erable commitment to, or psychological investment in, the status quo option" (Samuelson & Zeckhauser, 1988, p.10), while the omission bias postulates that the status quo bias captures the tendency to decide in favour of the option which requires the least action. Both biases suggest that the decision-maker shows a behaviour, which can be similar to that of decision inertia (repeating a suboptimal decision without considering the consequences). However, decision inertia is not status quo bias, even if it may manifest in some situations as a tendency to favour the status quo. One argument for of differentiating between decision inertia and status quo bias is the fact that in many decision environments for decision inertia research do not contain a current state, no status quo option, and both options are linked to action (see e.g. Alós-Ferrer et al. (2016), Charness and Levin (2005)). Thus, when decision-makers in such environments exhibit inertia, the underlying process cannot be related to status quo bias but rather to a tendency to repeat previous decisions regardless of the consequences. Consequently, in many studies participants cannot rely on status quo bias, despite that they show a tendency to repeat their previous strategy. Another argument for distinguishing the two concepts is provided by the experiments of Maltz, Romagnoli, et al. (2015), illustrating further evidence against the cur-
rent conceptualization of status quo bias in judgement and decision-making research, per se. In a series of experiments, Maltz and Romagnoli investigated the status quo bias in risk-setting and under changing ambiguous conditions. They conclude that status quo bias disappears in games where both alternatives are risky, or both ambiguous (Maltz et al., 2015). These findings agree with those of with other studies, which postulate that "inertia acts like a status quo bias" (Dutt & Gonzalez, 2012, p.1), consequently I argue that decision inertia it offers a promising path to explain the mixed findings regarding the status quo bias, because it is one part of the underlying process driving the observed status quo tendency of decision-makers.
Habit:A habit is an “attachment to, and persistence of, existing behavioural patterns (some of which are habituated) even if there were better alternatives and incentives to change” (Polites & Karahanna, 2012, p.22). This definition assumes that decision-maker can rely on habits they have built in judgement and decision-making. Most decision inertia studies (see Section 4.2), rely on subsequent, tasks to measure decision inertia, where it seems not possible that decision maker could have enough time to build habits (which typically takes multiple days or weeks). Accordingly, Polites and Karahanna (2012) reason that inertia and habit must be considered differently in research, because habits are learned responses that are triggered automatically, hence it may be that inertia is driven by other factors.
Endowment Effekt:This bias describes the tendency of decision-maker to estimate the value of something to be greater if they own that thing (Kahneman, Knetsch, & Thaler, 1990). Thus, one could argue that decision inertia is partly explained by overestimation. However, this claim might not fully explain decision inertia, because decision inertia is about repeating de- cisions, not about appreciating a good. Moreover, the different experimental designs do not suggest that the participants had a feeling of ownership because they choose between different strategies, urns and so on. Furthermore, participants typically value both options the same at the outset of a study of decision inertia (showing no endowment). Hence, if at all, biased prob- ability estimation by the participants could be a possible explanation. In addition, studies on the endowment effect suggest that the effect is driven by different references points (Carmon & Ariely, 2000), which are not of explanatory value in current decision inertia studies.
Choice Deferral: Describes the tendency of decision-makers facing a difficult decision to make no choice at all (Dhar & Nowlis, 1999). Consequently, a decision-maker facing a difficult decision without a defer option, would probably select a random option. This option can also be the previous decision, which than is equal to decision inertia. In such a case, decision inertia and choice deferral behaviour would probably overlap. However, this kind of behaviour would also mean, that other types of errors increase in such scenarios, because the decision- maker chooses randomly. This possibility has not been observed in decision inertia research. Furthermore, decision inertia and choice deferral can be separated into distinct outcomes if a no-decision option were provided. I did this in Section 4.4, and found no significant influence of this feature on biased decision-making. Hence, it seems reasonable that decision inertia and choice deferral might have shared drivers, but they are distinct biases caused by different factors.
Inaction Inertia:Another phenomena that has some behavioural overlap with decision iner- tia is inaction inertia. Inaction inertia is definied as "when bypassing an initial action oppor- tunity has the effect of decreasing the likelihood that subsequent similar action opportunities will be taken" (Van Putten, Zeelenberg, van Dijk, & Tykocinski, 2013, p.1). In particular, in- action inertia has great implications for marketing, as it suggests that discount campaigns increase willingness to buy in the short term, but reduce the willingness to buy when they expire. Customers who learn about the campaign afterwards are no longer interested in the product. Furthermore, inaction inertia can influence the behaviour of investors who missed the option to switch strategy in a market (Tykocinski, Israel, & Pittman, 2004). The central difference to decision inertia is that the experimental paradigms that generate inaction inertia presuppose an opportunity has been missed and that the circumstances have changed. Fur- thermore, the participants do not choose by themselves, they are always presented a short text describing their past actions. Hence, they never really "make" a first decision. Decision inertia tasks do not use this kind of mindset. In their tasks, participants choose between op- tions, which stay the same across the whole experiment, as the probability distributions and outcomes. Furthermore, participants make real decisions, and are generally not faced with descriptions what they have done or will do. Thus inaction and decision inertia can have the same behavioural consequence in specific cases, but different cognitive processes can be assumed here.
Indecisiveness: Indecisiveness is decision-makers’ inability to make a decision in a timely manner across situations and domains (Frost & Shows, 1993). It is a personal trait used in diagnostic psychology to predict behaviour across many domains. In the context of decision inertia, it is possible that individuals who experience more indecisiveness will have a greater likelihood of repeating previous decisions regardless of the consequences. In this case, in- decisiveness assumes that decision-makers show decision inertia when they are indecisive. Following this hypothesis, decision inertia is therefore caused by an evasion of a decision or responsibility for it. It seems possible that this might explain different aspects of decision inertia, so, I examine that relationship in more detail in Section 4.4.
4.2
Measuring Decision Inertia in a Dual-Choice Paradigm
In judgement and decision-making research, there exist various approaches to measure the behavioural or cognitive outcomes of decision inertia in experimental tasks (see, Tables 9, 10, and 11). A deeper investigation of these tasks shows, that the distinct streams investigate be- haviour as a proxy for the manifestation of decision inertia under very different circumstances, for example decision inertia after reception of visual information (Akaishi et al., 2014), deci- sion inertia as a failure in belief-updating (Alós-Ferrer et al., 2016; Charness & Levin, 2005) and confidence in beliefs (Pitz & Barrett, 1969; Geller & Pitz, 1968; Pitz et al., 1967), as an increase in response-time (Alós-Ferrer et al., 2016; Achtziger et al., 2012), or as reluctance to switch away from an option after information (Dutt & Gonzalez, 2012), as tendency towards choice
repetition in economic risk games (Erev & Haruvy, 2013; Erev et al., 2010) and so on. As a con- sequence, the measurement of decision inertia varies widely, and it remains unclear whether the same results hold in other experimental settings, and if whether they are generalizable at all.
Thus, I present a neutral and reliable setting to induce and reproduce decision inertia. Further- more, this paradigm allows one to vary the possible drivers of decision inertia easily. For that purpose, I offer a short overview of the most relevant tasks of recent decision inertia research, and discuss their practical value for further decision inertia research. Finally, I summarize recent decision inertia tasks, and based on these findings I derive a framework (dual-choice paradigm) for the analysis of decision inertia for subsequent decisions in the lab.