PHYSICIANS' JUDGMENTS OF RADIOLOGICAL IMAGES ON A MULTI-TRIAL DISCRIMINATION TASK: EVIDENCE FOR THE USE OF COGNITIVE HEURISTICS

Background: Decades of research on perception and prediction of randomness led us to speculate that various response strategies, or heuristics, observed in these studies might manifest in multi-trial discrimination tasks used in medical education. In the face of uncertainty, relying on cognitive heuristics such as win-stay/lose-shift and win-shift/lose-stay can improve performance relative to chance. Various combinations of stimulus alternation rate and marginal distribution create conditions where certain heuristics will be optimal and others counterproductive.

Purpose: We demonstrate that by varying stimulus sequence features, namely the marginal distribution and alternation rate of normal and abnormal radiological images presented in a discrimination task, it is possible to induce physicians to exhibit predictable response patterns that are consistent with win-stay/lose-shift and win-shift/lose-stay heuristics.

Methods: A convenience sample of 46 physicians and medical students participated in an online serial learning task. Two-hundred-thirty-four digitized pediatric ankle radiographs, providing a case-mix frequency of variant images consistent with that seen in actual clinical practice, were uniquely ordered for each subject. On each trial subjects were provided with the presenting complaint and clinical findings of the case, followed by three views of the patient's ankle. Subjects classified each case as normal or abnormal and then received feedback. The data from each subject were examined for sequential response patterns. For trials 2 through 234 the response on the current trial was classified as being the same or different from the response given on previous trial. Repeated-response trials were grouped according to whether the subject was correct or incorrect on the previous trial and aggregated for analysis. If the proportions of repeated-responses following correct trials were found to be significantly greater than those following incorrect trials this would provide evidence consistent with the win-stay/lose-shift heuristic; the opposite pattern would be consistent with win-shift/lose-stay.

Results: Physicians and students exhibited response patterns consistent with win-stay/lose-shift and win-shift/lose-stay heuristics. In most cases individuals were more likely to repeat a response if it was correct on the previous trial than if it was incorrect. These patterns were found to significantly covary, in predictable ways, with stimulus alternation rates and marginal distributions.

Conclusions: Varying the alternation rate and marginal distribution of radiological images in serial discrimination tasks can differentially induce predictable response patterns among physicians asked to interpret these images.