Past research has shown that emotion affects preferential choice outcomes. The goal of the present study was to further research on emotion and preferential choice by using mathematical modeling to investigate the effects of specific dimensions of emotion on the underlying mechanisms of preferential choice. Specifically, we aimed to determine whether the concurrent effects of positive-negative valence and situational certainty on attention and information accumulation threshold, respectively, would influence the magnitude of the similarity effect, a robust phenomenon in preferential choice. Participants first underwent either an Anger (negative and certain), Fear (negative and uncertain), or no (Control) emotion manipulation. All participants then completed an apartment choice task that was designed to elicit the similarity effect. A novel framing manipulation was used to test the effects of emotional valence on attention. Both feature framing and emotion condition significantly affected choice outcomes. These results suggest differences in deliberation style between Anger and Fear participants, as well as a surprising impact of alternatives outside the choice set on choice outcomes. Future directions are discussed.