Ordered to attract: The dynamics of attraction effect in simultaneous and sequential value-based choice tasks

The attraction effect refers to the impact of an asymmetrically dominated irrelevant option (decoy) in shifting preferences towards its dominant option (target), with respect to another, non-dominant alternative (competitor). This context effect has been observed in multiple studies, yet its practical relevance in real-life situations has recently been questioned, since various factors can modulate, nullify, or even reverse the attraction effect. In this study, we investigate the impact of presentation order and presentation modality (simultaneous or sequential) on the elicitation of the effect in a value-based choice task. Previous studies documented the relevance of these variables in modulating the effect, yet they used perceptual discrimination tasks, raising the question of whether these factors would have the same impact on value-based choice. Our findings confirm that spatial proximity between target and decoy is necessary for eliciting attraction effects in value-based choice (as it is in perceptual discrimination) when options are presented simultaneously; however, when options are presented sequentially, temporal proximity is showed to be irrelevant for the attraction effect, which is observed across all presentation orders (contrary to what was reported in previous studies using perceptual discrimination tasks). These results provide further insight on the importance of both visual arrangement, task demands, and cognitive processing in modulating context effects in decision-making.