Abstract

Prolonged or intense oculomotoric muscle use may cause strain. This strain is rearly perceived because at many visual tasks the strain remains subliminal due to the small amount by which the eyes are displaced from their muscular equilibrium. However, some visual tasks require a large angular displacement of the eyes in relation to the head. In such cases, the displacement is not maintained for a long time. Either the eyes move back to their initial position or, if the point of fixation has to be maintained, head movements are performed in order to compensate the displacement of the eyes in relation to the head. Hartmann (1987) showed that with an increasing angular change of the direction of fixation, eye displacement is increasingly achieved by the help of head movements. If only an energetically point of view is considered, changes in direction of fixation should preferably be carried out by movements of the eyes rather than by movements of the head due to the big difference between the moment of inertia of the eyes and the one of the head.

© 1992 Optical Society of America