A General End-to-End Method for Characterizing Neuropsychiatric Disorders using Free-Viewing Visual Scanning Tasks

The growing availability of eye-gaze tracking technology has allowed for its employment in a wide variety of applications, one of which is the objective diagnosis and monitoring of neuropsychiatric disorders from features of attentional bias extracted from visual scanning patterns. Current techniques in this field are largely comprised of non-generalizable methodologies that rely on domain expertise and study-specific assumptions. In this paper, we present a general, data-driven, end-to-end framework that extracts relevant features of attentional bias from visual scanning behaviour and uses these features to classify between subject groups with standard machine learning techniques. The general framework uses visual scanning data from free-viewing tasks. In these tasks, subjects look at sets of slides with several thematic images while their visual scanning patterns (sets of ordered fixations) are monitored by an eye-tracking system. Subjects' fixations are encoded into relative visual attention maps (RVAMs), and two data-driven methods are proposed to segment regions of interests (ROIs) from RVAMs: 1) using group average RVAMs, and 2) using differences of group average RVAMs. Relative fixation times within the segmented ROIs are then used as input features for a vanilla multilayered perceptron to classify between patient groups. The methods were evaluated on data from two studies: an anorexia nervosa (AN)/healthy controls study (AN study) with 37 subjects, and a bipolar disorder (BD)/major depressive disorder (MDD) study (BD-MDD study) with 73 subjects. Using leave-one-subject-out cross validation, the general methods achieved an area under the receiver operating curve (AUROC) score of 0.935 for the AN study and 0.888 for the BD-MDD study, the latter of which exceeds the performance of the state-of-the-art analysis model designed specifically for the BD-MDD study, which had an AUROC of 0.879. The results validate the proposed framework's efficacy as a generalizable, standard baseline for analyzing visual scanning data.