"Set" theory: The neural and behavioral basis of how we evaluate non-choice sets and choice sets.
Recent research suggests that we may automatically appraise, or mentally represent, the value of potential choice options, even when they are not explicitly part of a decision. Here we explore some of the implications of these findings in two streams of research. In one set of studies, we examine the effects of display-only items that are present during a decision, but not explicitly available as choice options. We find that such “display sets" are still able to influence the likelihood of purchasing a target product. However, the nature of their influence arises from their similarity to the target, and not by their relative value, in contrast to the predictions of several behavioral and neural models. In a second line of studies, we combine fMRI and behavioral methods to examine the whether people estimate set value in differing ways when they are browsing (e.g. appraisal) vs. buying (e.g. choice). We find evidence that average liking for the items in a four-item set is reflects the average value of the individual items, and evokes similar neural activity across both appraisal and choice tasks. However different brain areas (e.g. mOFC) are more active and/or recruited specifically when participants have to make a choice. This research suggests that the representation of value might be calculated in qualitatively different ways based on their task, or goal.