EFFECTS OF MULLER-LYER ILLUSION ON THE ACCURACY OF PRIMARY SACCADES AND SMOOTH PURSUIT EYE MOVEMENTS

Abstract

The goal of the present investigation was to evaluate the effect of visual Muller-Lyer (M-L) illusion on the control of saccadic and smooth pursuit eye movements and compare it with the results obtained during perceptual judgment of the length of the shaft of M-L illusion. Experimental investigation revealed that the primary saccades elicited in the reflexive mode were mostly affected by the M-L illusion. The position errors of the primary saccades elicited in the reflexive mode were affected by 4% for wings-in illusion and by 3.6% for wings-out illusion comparing with the 0.25% and 0.1% for the saccades elicited in the voluntary mode. The position errors of complete saccades (0.14% and 0.02%) and tracking errors obtained during the smooth pursuit (0.11% and 0.05%) were negligibly small. Nevertheless, experimental results obtained during perceptual judgment of M-L illusion were substantially larger - 14% and 10% respectively. The obtained results have demonstrated that vision for perception and vision for action were executed by different neural networks and supported the two-visual-system hypothesis.DOI: http://dx.doi.org/10.5755/j01.itc.41.1.763