Abstract
When making decisions under uncertainty, people in all walks of life, including highly trained medical professionals, tend to resort to using ‘mental shortcuts’, or heuristics. Anchoring-and-adjustment (AAA) is a well-known heuristic in which subjects reach a judgment by starting from an initial internal judgment (‘anchored position’) based on available external information (‘anchoring information’) and adjusting it until they are satisfied. We studied the effects of the AAA heuristic during diagnostic decision-making in mammography. We provided practicing radiologists (N = 27 across two studies) a random number that we told them was the estimate of a previous radiologist of the probability that a mammogram they were about to see was positive for breast cancer. We then showed them the actual mammogram. We found that the radiologists’ own estimates of cancer in the mammogram reflected the random information they were provided and ignored the actual evidence in the mammogram. However, when the heuristic information was not provided, the same radiologists detected breast cancer in the same set of mammograms highly accurately, indicating that the effect was solely attributable to the availability of heuristic information. Thus, the effects of the AAA heuristic can sometimes be so strong as to override the actual clinical evidence in diagnostic tasks.
Highlights
One of the most impactful insights from several decades of research in human judgement and decision-making is that human beings do not always act as rational decisionmakers but often resort to using heuristics when making decisions under uncertainty or under time pressure [1,2,3,4,5,6]
Study 1: Characterization of the effect of the anchoring and adjustment (AAA) heuristic on detection of cancer in mammograms by practicing radiologists In Study 1, practicing radiologists (n = 12) were shown a randomly generated number between 0 and 100 on a computer monitor. They were told this was the percent chance estimated by another radiologist that the upcoming mammogram contained cancer (‘purported prior estimate ψ’; Figure 1A, left panel, top)
The subjects viewed the actual mammograms for various durations (0.2 s, 0.5 s, 1 s, 5 s, 10 s, or 60 s, depending on the trial; Figure 1A, middle panel); after which, they entered their estimate that the mammogram they had just viewed contained cancer (‘subject’s final estimate β’; Figure 1A, right panel)
Summary
One of the most impactful insights from several decades of research in human judgement and decision-making is that human beings do not always act as rational decisionmakers but often resort to using heuristics (or mental shortcuts) when making decisions under uncertainty or under time pressure [1,2,3,4,5,6]. The use of heuristics is a fundamental faculty of the human mind and is known to occur in many diverse areas of decision-making and in novice subjects, as well as highly trained experts [7], including research scientists [2,3,4] and medical professionals [8,9]. Previous studies have characterized the effects of some of the heuristics in clinical settings [9,12,13]. The role of the AAA heuristic in clinical decision-making remains poorly understood. The present pilot study aimed to help fill this gap by characterizing whether and to what extent the AAA heuristic affects diagnostic decision-making, using mammographic decision-making by practicing radiologists as an illustrative example (see Discussion for additional caveats)
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