Lit, A. and Vicars, W. M. The Effect of Practice on the Speed and Accuracy of Equidistance Settings. American Journal of Psychology, 1966, 79, 464 - 469.
Copyright (c) 1966, The Board of Trustees of the University of Illinois.
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by John Michael Williams, 1999. Placed in public domain.
Two observers were asked to make numerous stereoscopic
distance settings in Lit's Pulfrich apparatus, at a distance of about
one meter, with instructions emphasizing accuracy. Eighteen 2-hour
sessions in a row were followed by another ten in a row after an
intervening period of five weeks.
The constant error (a term in the "personal equation") of each observer
was found to have decreased with time, apparently approaching zero with
sufficient practice, even though observers never received feedback on
their accuracy.
No important response time trend was found for these two observers.
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