Revisiting the Open Sampling format: Improving risky choices through a novel graphical representation

Kevin E Tiede,Felix Henninger,Pascal J Kieslich

doi:10.3758/s13423-021-02018-4

Abstract

When making risky choices, people often fall short of the norm of expected value (EV) maximization. Previous research has shown that presenting options in the Open Sampling (OSa) format, a 10-by-10 matrix of randomly arranged outcomes, can improve choices and reduce decision times. First, the current research aims to replicate and extend the findings on the OSa format. To this end, we compare OSa to the common description-based format as well as further graphical representations, and investigate the resulting accordance with EV maximization and decision time. Second, we study whether people lower (vs. higher) in numeracy, the ability to use probabilistic and mathematical concepts, particularly benefit from a graphical representation of options. We conducted five high-powered studies (total N = 1,575) in which participants chose repeatedly between two risky gambles, using different populations and gamble-problem sets. Overall, we could not find a benefit of the OSa format in terms of EV accordance in any of the five studies. However, three studies also tested a novel variant of the OSa format with grouped outcomes and found that it consistently improved EV accordance compared with all other formats. All graphical formats led to faster decisions without harming decision quality. The effects of presentation format were not moderated by numeracy in three of the four studies that assessed numeracy. In conclusion, our research introduces a new presentation format which consistently improves risky choices and can also be used to communicate risks in applied contexts such as medical decision making.

Highlights

Decisions under risk, where any of several outcomes can occur with known probabilities, are a common occurrence in every-day decision-making, ranging from the decision whether to carry an umbrella, or purchase an insurance, to choosing a promising but experimental medical treatment
We evaluate the effects of additional graphical representations of risky choice, seeking to determine which of Open Sampling (OSa)’s features may be responsible for the observed benefits
While numeracy was positively related to expected value (EV) accordance in both studies (Study 1a: b = 0.02, SE = 0.01, p < .001; Study 1b: b = 0.02, SE = 0.00, p < .001), it moderated the effect of presentation format on EV accordance in Study 1b only (b = −0.02, SE = 0.01, p = .005), and not in Study 1a (b = −0.01, SE = 0.01, p = .380)

Summary

Introduction

Decisions under risk, where any of several outcomes can occur with known probabilities, are a common occurrence in every-day decision-making, ranging from the decision whether to carry an umbrella (lest it rain), or purchase an insurance (to be safe in an unlikely emergency), to choosing a promising but experimental medical treatment. Hilbig and Glöckner demonstrated in two studies that OSa resulted in the most even treatment of small probabilities compared with a tabular summary (description; see Fig. 1a) and sampling a single outcome at a time (decisions from experience; Hertwig et al, 2004) In both studies, choices “conformed more to the normative hallmark of expected value maximization” Gaining a more detailed picture of the process through which OSa achieves its benefits will provide a deeper understanding of the processes at work, for example whether its reliance on natural frequencies (which have been demonstrated to facilitate Bayesian reasoning; Gigerenzer & Hoffrage, 1995) is the driving factor, or possibly the shuffled arrangement of values (as argued by Hilbig & Glöckner, 2011) Once these processes are known, additional possibilities for improvements may arise from further, novel, presentation formats. We expect that numeracy moderates the effect of format on EV accordance

Participants

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Discussion