Looking at the task in hand: vergence eye movements and perceived size

Abstract

A retinal afterimage of the hand changes size when the same unseen hand is moved backwards and forwards in darkness. We demonstrate that arm movements per se are not sufficient to cause a size change and that vergence eye movements are a necessary and sufficient condition for the presence of the illusory size change. We review previous literature to illustrate that changing limb position in the dark alters vergence angle and we explain the illusion via this mechanism. A discussion is provided on why altering limb position causes a change in vergence and we speculate on the underlying mechanisms.

Neuroanatomical correlates of voluntary inhibition of accommodation/vergence under monocular open‐loop viewing conditions

“…Another subject exhibited rightward versional eye movements. Some of our subjects may have exerted voluntary control over vergence in order to produce negative accommodation, whereas others may have exerted voluntary control over accommodation in order to achieve divergence (Mon‐Williams et al ., 1997).…”

“…The process of adjusting the curvature of the crystalline eye lens to bring images into sharp focus in the plane of the retina is called accommodation (Crawford et al ., 1989; Kaufman, 1992; Gamlin et al ., 1994; Mays & Gamlin, 1995; Ciuffreda, 1998; Ohtsuka et al ., 2002). Under normal viewing conditions, both spatiotopic (‘feedforward’) and retinotopic (‘feedback’) cues drive the accommodation/vergence response of the human eye lens (Toates, 1972; McLin et al ., 1988; Kruger et al ., 1997; Mon‐Williams et al ., 1997; Lee et al ., 1999; Stark et al ., 2002; Rucker & Kruger, 2004). Shifts of attention guide the eye to a target of interest and the lens of the eye assumes a more concave shape when gaze is directed at, e.g.…”

Looking at the task in hand impairs motor learning

“…These findings raise the question of the neurophysiological mechanisms by which visual capture is interfering with learning. The human nervous system is adept at incorporating multiple sources of information to control skilled actions and adjusting the weighting attached to information on the basis of its reliability Mon-Williams et al 1997a;Wilkie and Wann 2005). During the Direct viewing condition the combined visual-motor estimate will be much less noisy than during Indirect viewing, and so both visual and haptic signals are weighted highly (and so are difficult to ignore).…”

3D Gaze Tracking and Analysis for Attentive Human Computer Interaction

“…These techniques are These techniques are for gaze tracking for 2D screen or images. The researches on eye vergence also have been reported [5] [6]. In [6], the monitoring system of eye vergence is implemented with HMD (Head Mounted Display).…”