Publications

A new method for categorizing scanpaths from eye tracking data

Haass, Michael J.; Matzen, Laura E.; Butler, Karin B.; Armenta, Mika

From the seminal work of Yarbus [1967] on the relationship of eye movements to vision, scanpath analysis has been recognized as a window into the mind. Computationally, characterizing the scanpath, the sequential and spatial dependencies between eye positions, has been demanding. We sought a method that could extract scanpath trajectory information from raw eye movement data without assumptions defining fixations and regions of interest. We adapted a set of libraries that perform multidimensional clustering on geometric features derived from large volumes of spatiotemporal data to eye movement data in an approach we call GazeAppraise. To validate the capabilities of GazeAppraise for scanpath analysis, we collected eye tracking data from 41 participants while they completed four smooth pursuit tracking tasks. Unsupervised cluster analysis on the features revealed that 162 of 164 recorded scanpaths were categorized into one of four clusters and the remaining two scanpaths were not categorized (recall/sensitivity=98.8%). All of the categorized scanpaths were grouped only with other scanpaths elicited by the same task (precision=100%). GazeAppraise offers a unique approach to the categorization of scanpaths that may be particularly useful in dynamic environments and in visual search tasks requiring systematic search strategies.