Every effort has been taken to ensure that these materials comply
with the requirements of copyright clearances and appropriate
credits. Athabasca University will attempt to incorporate in future
printings any corrections which are communicated to it.
The inclusion of any material in this publication is strictly in
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The
quote from
Keller (1968) is reprinted with the permission
of the Journal of Applied Behavior Analysis.
© Athabasca University 2000
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Printed in Canada
Course Team
Module Author: David Polson
Course Coordinator/Technical Advisor: Lyle Grant
