Choice-supportive misremembering: A robust phenomenon?

Although the literature on choice-supportive memory – remembering the items of chosen options as more preferential and those of non-chosen options as less preferential than they actually were – is scarce and scattered, it has widely been accepted as a solid phenomenon that could lead to biased future decisions. In the published studies to date, different types of such misremembering have been observed using rather dissimilar methods, with the large majority testing memory solely with source recognition. The characteristics of the material to be remembered have not been particularly varied and the effect of different delay levels has not been properly investigated. Thus, at the onset of this project, there was a lack of insight into the nature and robustness of the phenomenon and no systematic review of the relevant literature had been done to provide an integrative assessment of its status. The objectives and scope of the current project are the following: (1) to conduct a systematic literature review on the phenomenon of choice-supportive misremembering; (2) to propose a new comprehensive taxonomy of the different types of memory distortions after choice, and (3) to investigate the empirical support for the proposed taxonomy and explore the conditions necessary for the choice-supportive misremembering effect. The first experiment involved four choice scenarios and had a typical design for studies in the decision-making literature (information presented in tables with a low number of attributes and only the value of each one differing between the two options). Memory was tested with free and cued recall only, and the delay between the choice and the memory tests was manipulated on three levels (2 minutes, 20 minutes, and 2 days). The results fully supported the proposed taxonomy, but also highlighted the absence of choice-supportive misremembering despite the high statistical power of the tests. In the second experiment, the scenarios and options were more complex and verbose, with a higher number of items. Four different scenarios were used and presented in two different formats (‘narrative’ vs list) as well as in an alignable and an unalignable version. The narrative versions presented the items of the two options in blocks of text (Option A above Option B), whereas the list versions displayed each item on a separate line (Option A adjacent to Option B). In the alignable version, the items presented had corresponding items on the same dimension in both options, while there was no such correspondence in the unalignable version. This time, memory was tested with free and cued recall in addition to a source recognition test that has hitherto been more typical for studies on choice-supportive misremembering. In common with the first study, this second experiment provided full support for the proposed taxonomy, but it also demonstrated the existence of the choice-supportive misremembering effect regardless of the manipulated variables. Considered in unity, the results of the two experiments suggest that the type of stimuli used is a decisive factor and confirm that the phenomenon does not occur with the kind of materials typically used in the decision-making literature. Indeed, when participants are more likely to compare the options item by item rather than rely on gist-based processing, they do not seem to exhibit choice-supportive memory effects. This observation and the findings from the literature review and the two experiments are discussed in light of the various theories that have been proposed to explain misremembering. Finally, suggestions on how to further expand the knowledge through new research studies on specific populations are put forward.