Externally provided rewards increase internal preference, but not as much as preferred ones without extrinsic rewards

It is well known that preferences are formed through choices, known as choice-induced preference change (CIPC). However, whether value learned through externally provided rewards influences the preferences formed through CIPC remains unclear. To address this issue, we used tasks for decision-making guided by reward provided by the external environment (externally guided decision-making; EDM) and for decision-making guided by one’s internal preference (internally guided decision-making; IDM). In the IDM task, we presented stimuli with learned value in the EDM and novel stimuli to examine whether the value in the EDM affects preferences. Stimuli reinforced by rewards given in the EDM were reflected in the IDM’s initial preference and further increased through CIPC in the IDM. However, such stimuli were not as strongly preferred as the most preferred novel stimulus in the IDM, indicating the superiority of intrinsically learned values (SIV). The underlying process of this phenomenon is discussed in terms of the fundamental self-hypothesis.Author SummaryWe make decisions based on internal value criteria, which are individual preferences, or based on external value criteria, which are the values learned from the external environment. Although it is known that values are learned in both types of decisions, is there a difference in the nature of these values? Our study uses simulation and fits human behavioral data to address this question. The results showed that stimuli that were learned to be highly valued because of external feedback became preferred in subsequent preference judgments. However, it is interesting to note that such stimuli were not chosen as much as stimuli that were preferred without influence from the external environment. This finding suggests that values formed through one’s own criteria have characteristics distinct from those formed through external environmental influence. Our findings promote an integrated understanding of the decision-making process.