Assessment of Changes in Visual Object Perception by Analysis of Saccadic Eye Movements
Tegetmeyer H., Wenger A.
Dept. of Ophthalmology, Leipzig University
Purpose: Geometric-optical illusions produce deviations of visual perception from the real shape of the visual object. This is expressed in perceived distortions or length-changes of the object structures. The aim of this study was to investigate whether visually perceived length differences of Mueller-Lyer figures result in amplitude differences of saccadic eye movements along the figures.
Method: Mueller-Lyer figures (parallel lines of equal length with arrowheads on their ends pointing inward or outward, respectively) were presented in horizontal and vertical orientations in a distance of 1,25m and with a length of 15 deg. Video recordings of eye movements were obtained from 35 healthy volunteers (aged 18 30 years) when scanning the endpoints of Mueller-Lyer targets. The fixation periods between the saccades were adjusted at 1s and 4s.
Results: Saccades between the ends of lines with inward-pointing arrowheads were executed with significantly greater amplitudes than saccades between the ends of lines with outward-pointing arrowheads. This bias was observed for both horizontal and vertical target orientations. The target orientation did not significantly change the mean differences in saccadic amplitude neither for fixation periods of 1s (0.83deg horizontal and 0.71deg vertical) nor for fixation periods of 4s (0.45deg horizontal and 0.66deg vertical).
Conclusions: The analysis of saccadic eye mo
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