source activation

[Wolfgang Schoppek]

In my attempts to construct my own ACT-R (4.0) models I realized that I
don't understand the relation between "being the focus" and "source
activation". Hitherto I believed that only the chunk on top of the
goal-stack is a source of activation. But following the traces of a very
simple model I realized that pushing a chunk on the stack with
(Focus-on-Goal) does not raise the activation-level of the chunk.
Setting a source value with (sdp  :Source) causes such a raise without
the chunk being the focus. I couldn't find an answer to this question
neither in the literature nor in the manual. So can anybody help me with
my fundamental problem?

-- Wolfgang
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 Dr. Wolfgang Schoppek                <<< Tel.: +49 921 555003 <<<
 Lehrstuhl fuer Psychologie, Universitaet Bayreuth, 95440 Bayreuth
  http://www.uni-bayreuth.de/departments/psychologie/wolfgang.htm
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