Patricia Wollstadt, Martina Hasenjäger, Christiane Wiebel, "Quantifying Predictability of Scan Path Data using Active Information Storage", Entropy, vol. 23, no. 2, pp. 167, 2021.

Entropy-based measures are an important tool to study human gaze behavior under various conditions. Measures, such as the gaze transition entropy, are used to quantify the predictability of transitions between consecutive fixations. However, these measures do not account for temporal dependencies beyond interactions of order one. Therefore, we propose a novel approach to quantifying predictability in scanpath data by estimating the active information storage (AIS), which allows to account for temporal dependencies spanning multiple fixations. AIS is calculated as the mutual information between the past state of a process and its next value. It is thus able to measures how much information a sequence of past fixations provides about the next. Applying this approach to scanpath data recorded during a visual search task revealed significant temporal dependencies beyond interactions of order one and allowed to differentiate between induced observer states based on estimated AIS values.