Scaling of Horizontal and Vertical Fixational Eye Movements

TL;DR

This study analyzes the scaling properties of fixational eye movements using DFA, revealing differences between horizontal and vertical movements and the role of micro-saccades in persistence.

Contribution

It introduces the application of DFA to study fixational eye movements and uncovers how micro-saccades differently affect horizontal and vertical persistence.

Findings

Horizontal and vertical movements show different scaling behavior.

Removing micro-saccades makes horizontal and vertical scaling similar.

Micro-saccades increase short-term persistence mainly in horizontal movements.

Abstract

Eye movements during fixation of a stationary target prevent the adaptation of the photoreceptors to continuous illumination and inhibit fading of the image. These random, involuntary, small, movements are restricted at long time scales so as to keep the target at the center of the field of view. Here we use the Detrended Fluctuation Analysis (DFA) in order to study the properties of fixational eye movements at different time scales. Results show different scaling behavior between horizontal and vertical movements. When the small ballistics movements, i.e. micro-saccades, are removed, the scaling exponents in both directions become similar. Our findings suggest that micro-saccades enhance the persistence at short time scales mostly in the horizontal component and much less in the vertical component. This difference may be due to the need of continuously moving the eyes in the horizontal plane, in order to match the stereoscopic image for different viewing distance.