Abstract
Eye tracking systems have a large number of methods available to identify and visualize fixations, saccades, and scanpaths from individual participants in a study. However, methods to extract meaningful, statistically-significant group-level eye movement behaviors from a large cohort of subjects from multiple trials in a study are limited. Heat maps aggregate multiple trials over time, providing the means to visually identify fixations most common among multiple participants. However, heatmap methods discard the temporal view of the data, making it difficult to identify common patterns and trends in eye gaze behavior within subject groups, and even more challenging to compare gaze behavior between groups observing the same stimulus. We present a new method to extract frequent, significant trends in scanpaths from a cohort of participants observing static images. Our method is based on techniques used in the fields of sequential pattern mining and trajectory data mining, which are regularly used in mapping and navigation systems. Similar to how these systems analyze trends from large quantities of geospatial / global positioning system (GPS) data, our method analyzes eye tracking data from multiple subjects to identify frequently occurring scanpath trends. Identified trends are tested for statistical significance using bootstrap sampling. Scanpath trends are visualized, with p-values indicated, providing an easily interpretable plot for establishing the most significant trends among the cohort being evaluated. To validate the method, we implemented preliminary software in Python and evaluated eye tracking data collected from 60 participants observing a 2D static stimulus used in previous studies to characterize the visual attention of children exploring social objects [1]. All data were analyzed and trends plotted, revealing that the most significant scanpaths were those strongly trending toward social stimuli. [Figure 1, Supp]. Our method provides a useful tool for eye tracking researchers working with multiple participants observing identical stimuli.