Proceedings of the Annual Meeting of the Cognitive Science Society

In decision-making tasks with two attributes and three alternatives, the similarity effect implies that, if the totalexpected utility is equal between two opposite alternatives (i.e., the target and competitor), the probability of the target beingchosen decreases with the addition of the decoy similar to the target. This study demonstrated the similarity-compromiseeffect, wherein the probability of the target being chosen increased with the addition of the decoy, under the same conditionsas the similarity effect, by setting all attribute values of three alternatives to broken numbers rather than rounded numbers.To determine the mechanism underlying this effect, we examined information acquisition patterns using eye-movement datacollected from 37 undergraduates who made 10 hypothetical purchase tasks with two attributes and three alternatives. Time-series analysis of fixation time for the three alternatives revealed dynamic temporal features distinct from those of attractionand compromise effects observed in our previous research.