Motivated Interpretations of Survival Rates in Icon Arrays: An Issue of Frequency Format?

Abstract

Background

Icon arrays, which visually depict frequencies, are commonly recommended for communicating risk information such as survival rates. However, they have been found to be ineffective at buffering against motivated reasoning that can lead to undue optimism. To determine whether the impersonal frequency format of icon arrays (reporting a number affected out of a reference class) makes them vulnerable to motivated reasoning, a novel intervention is tested as a means for reducing undue optimism.

Methods

Female US participants from Amazon’s MTurk (N = 399) imagined a scenario in which their infant would be born extremely preterm. They were presented with icon array information about the survival chances (15-in-100 or 45-in-100) of prematurely born infants with intensive care. For the key intervention, some participants were asked a reflection question immediately after seeing the icon array, which prompted them to indicate what the information meant for their own infant’s percent-chance of survival (i.e., they converted a frequency about a reference class to a probability value about the personal outcome of interest). For other participants, the reflection question merely asked about frequency. The main dependent measure came next and assessed gut-level optimism.

Results

People’s gut-level beliefs about their infant’s chances of survival were optimistically biased; the intervention did not reduce this. These gut-level beliefs, rather than the objective survival rate information conveyed through icon arrays, were predictive of subsequent treatment choices.

Conclusions

The results suggest that the inability of icon arrays to buffer against motivated reasoning is not due to their frequency format. Moreover, the findings highlight the usefulness of measuring gut-level interpretations of likelihood, which can reveal significant insights into the psychological mechanisms driving patient-treatment choices.

Highlights

• Icon arrays, which visually depict frequencies, are commonly recommended as best-practice for communicating risk information in health contexts.

• However, recent work has found that they are ineffective at reducing the extent to which people engage in motivated reasoning when processing likelihood information.

• We find that the frequency format of icon arrays—depicting a rate for outcomes in a group of people rather than a case-specific probability—is not a primary reason why they are ineffective at reducing optimism bias

• We also find that measures of gut-level beliefs of likelihood are particularly well suited for detecting optimism bias, yet also predict subsequent treatment decisions.