Anticipated regret suppresses option collection: a breadth-depth framework for pre-decisional search

Although anticipated regret is known to regulate choice from a given set of options, its role in actively collecting those options remains largely unknown. This study proposed and tested a framework distinguishing regret over insufficient breadth (accelerator) from regret over insufficient depth (brake) in regulating the motivation to collect options. Two online experiments using an apartment selection task yielded clear evidence for the brake, but only indirect evidence for the accelerator. Experiment 1 showed that inducing regret over insufficient breadth led to higher collection motivation than inducing regret over insufficient depth. Experiment 2, using a control condition, showed that regret over insufficient depth significantly suppressed motivation relative to the control. By contrast, regret over insufficient breadth did not increase motivation beyond the control. Notably, however, participants reported a high default level of this regret even without induction and self-reported regret over insufficient breadth was significantly correlated with collection motivation, suggesting that it may operate as a persistent default rather than a manipulable accelerator. These findings clearly support the brake function and tentatively suggest that option collection is shaped by a selective brake against a default motivation to keep collecting, warranting further investigation of the accelerator function.