Perceptual compensation for eye torsion

• Published in: Vision research (Oxford) Vol. 45; no. 4; pp. 485 - 496
• Main Authors: Poljac, E., Lankheet, M.J.M., van den Berg, A.V.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-02-2005; Elsevier Science
• Subjects: Biological and medical sciences; Compensation; Eye Movements - physiology; Eye torsion; Fixation, Ocular - physiology; Fundamental and applied biological sciences. Psychology; Head Movements - physiology; Humans; Perceived location; Perception; Photic Stimulation - methods; Plane of regard; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Reference frame; Reflex, Vestibulo-Ocular - physiology; Rotation; Vision; Vision, Binocular - physiology; Vision, Monocular - physiology; Visual Perception - physiology; Perceived location; Reference frame; Eye torsion; Plane of regard; Compensation; Human; Gaze; Reference; Monocular vision; Experimental study; Eye; Visual system; Perception; Binocular vision; Torsion
• ISSN: 0042-6989; 1878-5646
• DOI: 10.1016/j.visres.2004.09.009

To correctly perceive visual directions relative to the head, one needs to compensate for the eye’s orientation in the head. In this study we focus on compensation for the eye’s torsion regarding objects that contain the line of sight and objects that do not pass through the fixation point.
Subjects judged the location of flashed probe points relative to their binocular plane of regard, the mid-sagittal or the transverse plane of the head, while fixating straight ahead, right upward, or right downward at 30
cm distance, to evoke eye torsion according to Listing’s law. In addition, we investigated the effects of head-tilt and monocular versus binocular viewing.
Flashed probe points were correctly localized in the plane of regard irrespective of eccentric viewing, head-tilt, and monocular or binocular vision in nearly all subjects and conditions. Thus, eye torsion that varied by ±9° across these different conditions was in general compensated for. However, the position of probes relative to the midsagittal or the transverse plane, both true head-fixed planes, was misjudged.
We conclude that judgment of the orientation of the plane of regard, a plane that contains the line of sight, is veridical, indicating accurate compensation for actual eye torsion. However, when judgment has to be made of a head-fixed plane that is offset with respect to the line of sight, eye torsion that accompanies that eye orientation appears not to be taken into account correctly.