70 AJUM May 2015 18 (2) Original research Introduction Visual search, the task of inding a target among distractors is commonplace in daily life. he processes involved in visual search have been studied extensively in laboratory settings and more recently in more real world settings on experts in a range of domains (e.g., airport luggage screening, 1 aeroplane piloting 2 and medical imaging 3 ). Radiologists are experts in visual search of medical images. hey are required to visually search a cluttered medical image and then make a diagnostic decision based on abstract anatomical features. his task demands a high accuracy of performance. To reach a level of expertise in image interpretation, comprehensive training and practice is required. All tasks that rely on human visual search are prone to error. When errors occur within medicine, the societal cost is high and so it is important to study the processes that underpin this type of search. Medical imaging practices are trending toward higher volume and increasingly complex examinations, meaning human errors could potentially increase. It has been reported in some areas within radiology that there may be up to 30% miss error rates and equally high false alarm rates. 4 In Australia, within the sub-specialty of ultrasound, medical sonographers perform the diagnostic scan, select images and present to the radiologist for reporting. his means that if the sonographer has not detected an abnormality, it cannot be diagnosed and reported. Among technologists, sonographers hold the unique responsibility of having to perform continuous visual and cognitive tasks, to make judgments and capture pathologies in real-time to ensure all relevant images are available for diagnosis by the radiologist. herefore, it makes sense to study sonographers, as the underlying cognitive and perceptual processes involved in the visual task are identical to radiologists and the potential for errors are similar. In regard to diagnostic accuracy, approximately 60% of all radiological diagnostic errors can be attributed to cognitive or perceptual errors. 5 A primary goal of image perception research in radiology has been to model the visual search strategies that radiologists use, in order to mitigate errors. he majority of studies have taken a perceptual approach, using eye tracking to quantify image perception. 6 Eye or gaze tracking is a method used to measure visual search behaviour, such as where an observer is focusing, how oten and length of time. Ann J Carrigan 1,2,4 BAppSc (MRS), GradDip Medical Sonography, BSc Psych (Hons) Patrick C Brennan 3 PhD Mariusz Pietrzyk 3 PhD Jillian Clarke 3 BAppSc (Hons), GradDip Medical Sonography, MHlthScEd Eugene Chekaluk 4 PhD 1 Perception in Action Research Centre & Department of Cognitive Science Macquarie University Sydney New South Wales Australia 2 ARC Centre of Excellence in Cognition & Its Disorders Macquarie University Sydney New South Wales Australia 3 Medical Image Optimisa- tion and Perception Group (MIOPeG) Discipline of Medical Imaging and Radiation Sciences Faculty of Health Sciences University of Sydney Sydney New South Wales Australia 4 Department of Psychology Macquarie University Sydney New South Wales Australia Correspondence to email ann.carrigan@mq.edu.au A ‘snapshot’ of the visual search behaviours of medical sonographers Abstract Introduction: Visual search is a task that humans perform in everyday life. Whether it involves looking for a pen on a desk or a mass in a mammogram, the cognitive and perceptual processes that underpin these tasks are identical. Radiologists are experts in visual search of medical images and studies on their visual search behaviours have revealed some interesting findings with regard to diagnostic errors. In Australia, within the modality of ultrasound, sonographers perform the diagnostic scan, select images and present to the radiologist for reporting. Therefore the visual task and potential for errors is similar to a radiologist. Our aim was to explore and understand the detection, localisation and eye-gaze behaviours of a group of qualified sonographers. Method: We measured clinical performance and analysed diagnostic errors by presenting fifty sonographic breast images that varied on cancer present and degree of difficulty to a group of sonographers in their clinical workplace. For a sub-set of sonographers we obtained eye-tracking metrics such as time-to-first fixation, total visit duration and cumulative dwell time heat maps. Results: The results indicate that the sonographers’ clinical performance was high and the eye- tracking metrics showed diagnostic error types similar to those found in studies on radiologist visual search. Conclusion: This study informs us about sonographer visual search patterns and highlights possible ways to improve diagnostic performance via targeted education. Keywords: diagnostic errors, medical imaging, sonographers, visual search.