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Cristina Ghirardo, Mauro Manassi, Teresa Canas-Bajo, William Prinzmetal, David Whitney; Simulated tumor recognition in mammograms is biased by serial dependence. Journal of Vision 2020;20(11):1202. doi: https://doi.org/10.1167/jov.20.11.1202.
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© ARVO (1962-2015); The Authors (2016-present)
In radiological screening, radiologists scan myriads of radiographs with the intent of recognizing and differentiating cancerous masses. Even though they are trained experts, radiologists’ human search engines are not perfect: average daily error rates are estimated around 3-5%. A main underlying assumption in radiological screening is that visual search on a current radiograph occurs independently on previously seen radiographs. However, recent studies have shown that our current perception is biased by previously seen stimuli (Fisher & Whitney, 2014; Liberman et al., 2014); the bias in our visual system to misperceive current stimuli towards previous stimuli is called serial dependence. Here, we tested whether serial dependence impacts recognition of tumor-like shapes embedded in actual radiographs. In order to simulate tumors, we created a morph stimulus set based on three canonical shapes (147 simulated tumors in total). On each trial, radiologists were presented with a mammogram containing a random simulated tumor in a random location. Observers were then asked to match the tumor shape they saw by picking the shape from a morph continuum. Twelve radiologists completed 250 trials each. We found that serial dependence affected observers’ recognition of simulated tumors; simulated tumors were perceived as biased towards the simulated tumors seen in previous radiographs for 1 and 2 trials back. Hence, radiological screening was biased towards radiographs presented up to 5-10 seconds ago. Furthermore, regression analysis showed that perception on an average trial was pulled 19% and 6% toward the 1-back and 2-back trials respectively. Taken together, these results suggest that some of the diagnostic errors exhibited by radiologists may be caused by serial dependence from previously seen radiographs.
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