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Gijs Bloemsaat
11-10-2002, 08:48 PM
Dear BIOMCH-L Browsers,

I have a question concerning the friction of a pen on a digitizer tablet
(Calcomp 9000).
In an experiment where subjects had to make a precise single fast movement
from one point to the other, axial pen pressure and velocity were measured.
A secondary cognitive condition was included. Motor performance of 2 groups
was investigated. Both groups performed the task at the same speed. Both
groups reacted on the 2nd condition with a 14 gram raise. However,
group_1 raised pen pressure from 142 to 158 grams, group_2 from 183 to 199
gram.

My question: Is the force increase required to move the pen along the
trajectory equal for both groups? My hunch is (but that is not scientific)
that group_2 will need disproportionate more force input -1- because of
the tablets' elastic properties, the tablet will spring back and the pen
point is pressed more into the tablet, thus more friction and -2- the
springing back curve and friction curve are not linear.

I will post a summary of responses.

Thanks,

Gijs Bloemsaat


__________________________________________________ _________
Gijs Bloemsaat
Nijmegen Institute for Cognition and Information
University of Nijmegen - Dept. of Experimental Psychology
Room B.01.02
P.O. Box 9104, 6500 HE Nijmegen, The Netherlands
Voice +31 (0)24 3612758 Fax +31 (0)24 3616066
E-mail bloemsaat@nici.kun.nl
__________________________________________________ __________

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