Uncovering the Computational Mechanisms Underlying Many-Alternative Choice

Abstract

How do we choose when confronted with many alternatives (e.g., choosing which soda to buy at the supermarket)? While studies of the decision mechanisms underlying two- to three-alternative choice are common in the literature, there is comparably little decision modeling work with larger choice sets, despite their prevalence in everyday life. Even further, there is an apparent disconnect between research in small choice sets, supporting a process of gaze-driven evidence accumulation, and research in larger choice sets, arguing for models of optimal choice, satisficing, and hybrids of the two. Here, we bridge this divide by comparing these models in a many-alternative value-based choice experiment with 9, 16, 25 or 36 choice alternatives. We find that human subjects' choice behaviour does not match the assumptions of satisficing or optimal choice, while a hybrid of the two captures response times and choices well. Yet, only a process of gaze-driven evidence accumulation is able to also accurately capture the observed association between gaze allocation and choices.

Optimal Allocation of Finite Sampling Capacity in Accumulator Models of Multialternative Decision Making

“…Nonetheless, for binary choice, reward is still maximized at even allocations in sequential sampling when options have not been unevenly sampled in the past (Fudenberg, Strack, & Strzalecki, 2018; Jang et al., 2021). On the other hand, when the number of alternatives is much higher than two, people choose to ignore many of the available options (Thomas, Molter, & Krajbich, 2021), consistent with our findings. Moreover, for fixed‐duration tasks, there is evidence that humans have a choice set of around five in sequential decisions (Reutskaja, Nagel, Camerer, & Rangel, 2011), even if their final allocation might be uneven.…”

“…Nonetheless, for binary choice, reward is still maximized at even allocations in sequential sampling when options have not been unevenly sampled in the past (Fudenberg, Strack, & Strzalecki, 2018;Jang et al, 2021). On the other hand, when the number of alternatives is much higher than two, people choose to ignore many of the available options (Thomas, Molter, & Krajbich, 2021), consistent with our findings.…”

The visual environment and attention in decision making.

“…This finding suggests that, even though we have presented set size as a visual factor, it may influence the decision process as a cognitive factor, by moderating the search stopping point. Prior studies on multialternative decision making (Reutskaja et al, 2011; Stüttgen et al, 2012; Thomas et al, 2020) suggest that decision makers may rely on satisficing or a hybrid of satisficing for determining when to stop a search process. However, neither satisficing nor the proposed hybrid satisficing models can account for our findings on set size effects since these models assume that stopping is independent of the set size.…”