Related Experiment Video
Updated: Oct 5, 2026

VisualEyes: A Modular Software System for Oculomotor Experimentation
Published on: March 25, 2011
Chameleon eye position obeys Listing's law
P S Sándor1, M A Frens, V Henn
1Neurology Department, University of Zürich, 8091-Zürich, Switzerland.
Abstract:
Listing's law (LL) states that 3D-eye positions lie in a plane, when they are described as single-axis rotations from the primary position. This implies that the degrees of freedom of eye movements are reduced from three to two. Various hypotheses exist, regarding the implementation of LL. These include facilitation of binocular vision, optimization of oculomotor control, and mechanical constraints in the orbit. We recorded the 3D-eye position during saccadic scanning in the chameleon, to investigate whether LL is valid in an animal with different anatomical and behavioral characteristics compared to primates. We show that in chameleons, the eye position obeys LL with a high precision. Since the anatomical arrangement of the orbit in chameleons is very different from that in primates, and binocular fused vision is virtually absent, we suggest that in the chameleon, LL mainly optimizes oculomotor control.
Related Concept Videos
Accessory Structures of the Eye
Anatomy of the Eyeball
Muscles of the Eye
Extraocular Muscles
The six extraocular muscles surround the eyeball and control its movements. They are responsible for a wide range of eye motions, including looking up, down, left, right, and rotating...
Nonconscious Mimicry
Position-effect Variegation
Perceptual Constancy
Size constancy is the recognition that an object remains the same size, even when its image on the retina changes. For instance, a bus is perceived to be large enough to carry people, even if it looks tiny from...

