Title: Effect of expertise and contralateral symmetry on the eye movements of observers while diagnosing Pneumoconiosis Authors:

Rationale: Pneumoconiosis 1 , a lung disease caused by the inhalation of dust is mainly diagnosed using chest radiographs. It has been shown 12 that expertise and contralateral symmetry (CS) of the chest radiographs plays a significant role in Pneumoconiosis diagnosis. Here, we present a gaze tracking study aimed at understanding how the CS information and the expertise effect the eye movements of observers. Methods: Experimental subjects consisting of novices, medical students, residents and staff radiologists were presented with 17 double and 16 single lung images, and were asked to give profusion ratings for each lung zone. Eye movements and the time for their diagnosis were also recorded. Results: Gaze tracking analysis showed that doctors [residents & staff] move eyes more quickly (MannWhitney test: U = 20, p = .01) and over more distances (U = 24, p = .022), when compared to that of non-doctors [others]. Wilcoxon signed rank test (Z = 4.19, p < .001), revealed that the average time taken for double lung images (Mdn = 30808ms) is less than double the time taken for single lung images (Mdn = 38385ms). Fixation time for zones correlates well with an observer’s certainty in judgment of the same as definitely normal or abnormal. Wilcoxon signed rank test (Z = 3.13, p = .001), showed the less fixation time on the zones of high observer error. Left and right lung gaze transitions correlates well with the observer error only in resident radiologists (r = -0.953, p = .047). Conclusion: CS information plays a very important role 12 in the case of residents & staff, while diagnosing pneumoconiosis. The present study showed that, for residents, the eye scanning strategies play an important role in using the CS information present in chest radiographs; however, in staff radiologists, peripheral vision or higher level cognitive processes seems to play role in using the CS information. * Contact email: [email protected]