Study of eccentric fixation with secondary visual feedback.

Secondary visual feedback (2VFB) is a visual signal derived from continuous measurement of eye position and provides an extra artificial indication of the point of gaze. 2VFB may be eccentrically displaced and subjects are able to visually superimpose 2VFB onto a visual target signal and thus achieve and maintain eccentric fixation. Initial transient patterns of movement depend upon training but even naive subjects can achieve eccentric fixation within the first 40 s of such a task. Individual strategies and idiosyncratic patterns are exaggerations of normal control and fixational eye movements. The variance of maintained fixation increases with eccentricity and appears to be related to visual acuity as well as to precision of ocular motor control.