Identification of Distinct Visual Scan Paths for Pathologists in Rare-Element Search Tasks

Background: The search for rare elements, like mitotic figures, is crucial in pathology. Combining digital pathology with eye-tracking technology allows for the detailed study of how pathologists complete these important tasks.

Objectives: To determine if pathologists have distinct search characteristics in domain- and nondomain-specific tasks.

Design: Six pathologists and six graduate students were recruited as observers. Each observer was given five digital "Where's Waldo?" puzzles and asked to search for the Waldo character as a nondomain-specific task. Each pathologist was then given five images of a breast digital pathology slide to search for a single mitotic figure as a domain-specific task. The observers' eye gaze data were collected.

Results: Pathologists' median fixation duration was 244 ms, compared to 300 ms for nonpathologists searching for Waldo (P < .001), and compared to 233 ms for pathologists searching for mitotic figures (P = .003). Pathologists' median fixation and saccade rates were 3.17/second and 2.77/second, respectively, compared to 2.61/second and 2.47/second for nonpathologists searching for Waldo (P < .001), and compared to 3.34/second and 3.09/second for pathologists searching for mitotic figures (P = .222 and P = .187, respectively). There was no significant difference between the two cohorts in their accuracy in identifying the target of their search.

Conclusions: When searching for rare elements during a nondomain-specific search task, pathologists' search characteristics were fundamentally different compared to nonpathologists, indicating pathologists can rapidly classify the objects of their fixations without compromising accuracy. Further, pathologists' search characteristics were fundamentally different between a domain-specific and nondomain-specific rare-element search task.