Complexity of eye fixation duration time series in reading of Persian texts: A multifractal detrended fluctuation analysis

TL;DR

This study investigates the multifractal nature of eye fixation durations during reading Persian texts, revealing that these dynamics are intrinsic to reading and largely unaffected by font, familiarity, or reading mode.

Contribution

It demonstrates that eye fixation durations exhibit multifractal behavior, indicating complex neural processes, and shows this pattern remains stable across different reading conditions.

Findings

Fixation durations show multifractal behavior.

Multifractal patterns are stable across reading conditions.

Mean fixation duration varies with some factors.

Abstract

There is growing evidence that cognitive processes may have fractal structures as a signature of complexity. It is an an ongoing topic of research to study the class of complexity and how it may differ as a function of cognitive variables. Here, we explore the eye movement trajectories generated during reading different Persian texts. Features of eye movement trajectories were recorded during reading Persian texts using an eye tracker. We show that fixation durations, as the main components of eye movements reflecting cognitive processing, exhibits multifractal behavior. This indicates that multiple exponents are needed to capture the neural and cognitive processes involved in decoding symbols to derive meaning. We test whether multifractal behavior varies as a function of two different fonts, familiarity of the text for readers, and reading silently or aloud, and goal-oriented versus non-goal-oriented reading. We find that, while mean fixation duration is affected by some of these factors, the multifractal pattern in time series of eye fixation durations did not change significantly. Our results suggest that multifractal dynamics may be intrinsic to the reading process.