Citation

Hocherman S, Levy H. Percept. Mot. Skills 2000; 90(3): 1235-1248.

Affiliation

Faculty of Medicine, Department of Physiology, Technion-Israel Institute of Technology, Israel. shraga@tx.technion.ac.il

Copyright

(Copyright © 2000, SAGE Publishing)

DOI

unavailable

PMID

10939075

Abstract

The role of visual feedback in manual tracking was investigated in 24 subjects who tracked 5-, 10-, and 40-mm/diameter targets, moving on a screen at 18 to 25 mm/sec., along various paths, by moving an unseen handle over a digitizing tablet. A cursor indicating instantaneous handle position was visible at all times on half the trials and hidden within a circle coaxial with the target but double its diameter in the other half. The handle had to be within the instantaneous target's digitizer-defined boundaries for the latter to keep moving. All tracking movements were segmented into small movement steps. A tendency to outrun the target was seen, indicating predictive control. Absence of visual feedback had negligible effect on movement velocity. Movement direction appeared to involve open-loop programming but improved significantly when subjects could see the cursor. Occasional corrective movements occurred only when visual feedback was given. Otherwise, a large positional error accumulates despite reasonable ability to control tracking direction.

Language: en