title: A method for studying the control of three-dimensional isometric forces using dynamic stereogram.
abstract: 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.
authors.affiliation: Department of Neuroscience, School of Medicine, Johns Hopkins University, Baltimore, MD 21205.
authors.forename: J T
authors.initials: JT
authors.lastname: Massey
authors.forename: G W
authors.initials: GW
authors.lastname: Hovey
authors.forename: W
authors.initials: W
authors.lastname: Schneider
authors.forename: J G
authors.initials: JG
authors.lastname: Chubbuck
authors.forename: A P
authors.initials: AP
authors.lastname: Georgopoulos
mesh_terms: D000669:Amplifiers, Electronic; D001330:Electronic Data Processing; D004581:Electronics; D004594:Electrophysiology / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D007537:Isometric Contraction; D009119:Muscle Contraction; D011597:Psychomotor Performance / Q000502:physiology*