A method for studying the control of three-dimensional isometric forces using dynamic stereogram

J. T. Massey, G. W. Hovey, W. Schneider, J. G. Chubbuck, A. P. Georgopoulos

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10 Scopus citations


A system has been developed for measuring the three-dimensional (3D) isometric forces produced by the arm in response to a visual stimulus. The output of 3 load cells is combined to determine the components of the 3D response force. The maximum force range of the load cells is 2000 g which can be read with a resolution of 4 g and with a measured accuracy of + / - 10 g. An overload stop protects the device to a load of 23 kg. The visual instruction to the subject concerning the direction and magnitude of the 3D force vector to be produced is presented using a vivid spherical stereogram. This stereogram is produced using the anaglyphic technique where the left and right images are separated by color filters. A dense aggregation of points defines the target cursor, which can be positioned anywhere inside or on the surface of the sphere. This cursor can represent a stationary or a moving target. A force feedback cursor can be provided to indicate to the subject his/her response. The color display on the cathode ray tube is produced by a display generator driven by a computer.

Original languageEnglish (US)
Pages (from-to)123-127
Number of pages5
JournalJournal of Neuroscience Methods
Issue number2
StatePublished - Dec 1988
Externally publishedYes

Bibliographical note

Funding Information:
This work was supportedb y USPHS Grants NS07226 and NS17413 which we gratefullya c-knowledgeD. r. J.T. Massey is also a membero f the Departmenotf BiomedicalE ngineeringT, he Johns Hopkins UniversityS choolof Medicine.


  • Isometric
  • Three-dimensional force
  • Three-dimensional visual stimulus
  • Upper limb


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