Expert radiologists can discern normal from abnormal mammograms with above-chance accuracy after brief (e.g. 500 ms) exposure. They can even predict cancer risk viewing currently normal images (priors) from women who will later develop cancer. This involves a rapid, global, non-selective process called “gist extraction”. It is not yet known whether prolonged exposure can strengthen the gist signal, or if it is available solely in the early exposure. This is of particular interest for the priors that do not contain any localizable signal of abnormality. The current study compared performance with brief (500 ms) or unlimited exposure for four types of mammograms (normal, abnormal, contralateral, priors). Groups of expert radiologists and untrained observers were tested. As expected, radiologists outperformed naïve participants. Replicating prior work, they exceeded chance performance though the gist signal was weak. However, we found no consistent performance differences in radiologists or naïves between timing conditions. Exposure time neither increased nor decreased ability to identify the gist of abnormality or predict cancer risk. If gist signals are to have a place in cancer risk assessments, more efforts should be made to strengthen the signal.
|Journal||Cognitive research: principles and implications|
|Publication status||Published - Dec 2021|
Bibliographical noteFunding Information:
This research was funded by Cancer Research UK and Engineering & Physical Sciences Research Council (EPSRC) Early Detection and Diagnosis Project award EDDCPJT/100027 to Karla K. Evans and by National Health and Medical Research Council (NHMRC), Australia Project Grant APP1162872.
EMR is funded through a departmental scholarship from the department of Psychology at the University of York, UK, for the 3-year duration of her PhD project. JMW was supported by NIH-NCI Grant CA207490. KKE was supported by Cancer Research UK and EPSRC Grant EDDCPJT\100027. These funding bodies had no influence on the design of the study and collection, analysis, and interpretation of data and in writing the manuscript.
We compared two experiments involving rapid assessment of the same set of image stimuli using two different groups of participants: novice and expert. The first experiment presented the images very briefly for 500 ms, while the second allowed unlimited viewing time but asked the observers to make a decision on the basis of their “first impression”. The main experimental observers were two groups of medical experts in radiology, and the control group was a group of observers without medical experience (“naïves”). Prior research has shown that naïve participants, without medical training, are unable to assess if a mammogram is abnormal or not in 500 ms (Evans, et al., , ). The control group allowed us to determine if naïve observers would have access to the “gist of abnormality” if they just had a bit more time. Radiologists were tested as part of the Medical Image Perception “pop-up” laboratory supported by the US NIH: National Cancer Institute at the annual meeting of the Radiological Society of North America (RSNA) in 2018 and 2019. The RSNA meeting presents a unique opportunity to test expert radiologists in numbers that are otherwise difficult to access. That opportunity comes with methodological constraints. A between-subjects design was needed as the RSNA setting did not allow for a sufficient time for ‘wash-out’ of memory for specific images between a first and second assessment of that image. Additionally, there is an inherent level of unpredictability of testing in such settings. This is reflected, for example, in the unequal numbers of observers in the two radiologist groups, one group tested in 2018, the other in 2019.
© 2021, The Author(s).
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