Two experiments examined the impact on the decoy effect of making salient thepossibility of post-decision regret, a manipulation that has been shown inseveral earlier studies to stimulate critical examination and improvement ofdecision process. Experiment 1 (N = 62) showed that making regret salienteliminated the decoy effect in a personal preference task. Experiment 2 (N =242) replicated this finding for a different personal preference task and for aprediction task. It also replicated previous findings that externalaccountability demands do not reduce, and may exacerbate, the decoy effect. Weinterpret both effects in terms of decision justification, with differentjustification standards operating for different audiences. The decoy effect, inthis account, turns on accepting a weak justification, which may be seen asadequate for an external audience or one’s own inattentive self butinadequate under the more critical review triggered by making regretpossibilities salient. Seeking justification to others (responding toaccountability demands) thus maintains or exacerbates the decoy effect; seekingjustification to oneself (responding to regret salience) reduces or eliminatesit. The proposed mechanism provides a theoretical account both of the decoyeffect itself and of how regret priming provides an effective debiasingprocedure for it.