Accession Number: 2012.psy.81
A brass instrument supported by a metal tripod base. The top element consists of a sphere that rotates on three axes. Each axis has a dial with four measurement quadrants, each marked 0-90 degrees. A fourth dial rests on a central optical piece at the centre of the sphere. This dial is connected to two antenna-like rods. The lens is removable. An optical chamber (camera obscura) runs through the centre of the sphere.
Alternative Name: Ophthalmotrop
Primary Materials: Brass, Metal
Dimensions (cm): Height = 59, Width (Diameter) = 24
This instrument demonstrates and quantifies one element of the mechanics of the human gaze, specifically the phenomenon of “pseudotorsion”: the torsion of the visual axes in the “tertiary positions of gaze” (right-up, right-down, left-up, or left-down) relative to a grid.
Manufacturer: Spindler & Hoyer, Germany
Date of Manufacture: c. 1921
Department of Psychology, University of Toronto
In 1846, Franciscus Cornelis Donders (1818-1889), at Dutch professor of Physiology, published a paper on eye muscle mechanics where he noted that the torsion of the visual field depended upon the amount of elevation or depression of the right or left gaze (pseudotorsion.) [Simonsz and den Tonkelaar, 96]
1) Simonsz, H. J., and I. Tonkelaar. 1990. 19th century mechanical models of eye movements, donders’ law, listing’s law and helmholtz’ direction circles. Documenta Ophthalmologica 74 (1): 95-112.
2)Wikipedia contributors, “Franciscus Donders,” Wikipedia, The Free Encyclopedia,(accessed February 10, 2012).