Attraction effect in crowded decision spaces: exploring the impact of decoys in choices among numerous options

Human choices are context-dependent, and options evaluation is biased by the quality and quantity of available alternatives. In the attraction effect, apparently irrelevant dominated decoys have proven effective in shifting preferences in numerous laboratory experiments, yet its relevance in real-life consumer choices remains disputed. Part of the problem lies in the differences between laboratory settings and realistic scenarios: in the lab, participants are typically tested on ternary choices, deliberately excluding any interference from other context effects; in contrast, in real life, consumers face choices among a high number of options, and interactions with other context effects are frequent. In this paper, we present two experiments that investigate how these factors modulate the attraction effect: in particular, we systematically manipulate the number of decoys (study1), and the number of options available to decision makers (study2). Our findings provide a rich map of the effects of asymmetrically dominated decoys in larger multialternative decision contexts, suggesting that: (i) the attraction effect remains significant for up to 5 options; (ii) two converging decoys are more effective than one, but (iii) adding more can undermine the effect; (iv) compromise options have a peculiar dampening influence on decoys, making them ineffective at targeting the intermediate option.