Restarting with non-zero Base Level Activations

[Tony J. Simon]

Folks
I am trying to run an ACT-R model a number of times with some (not all)
WME's starting out with the Base Level Activations that were reached by the
end of the previous run. I am having trouble figuring out how to do this
and wondered what help I could get. Here is the issue.

I am modeling infants' looking time responses to a task where 1-3 physical
objects are manipulated by an experimenter. The objects exist in the ACT-R
code as do the resulting mental representations, coded as "object files"
(though of course it would be better if only the latter were in ACT-R code
and the former in presented via LISP somehow). At the end of a run, the
object file WME's have certain levels of activation which affect production
match latency and this contributes to looking time. As a further test for
the model, I would like to do some "habituation" runs, i.e. repeat the task
N times with the prediction that looking time will decrease to asymptote by
N repetitions of the same outcome. This should happen just fine because all
the object file activations will increase and thus matching will be faster.

Here is the problem. The WMEs for the object files do not exist at the
start of the run. They are created when the model "sees" the physical
objects, and this happens at different times in different tasks. If I try
to create those objects (eg.  set baselevels for "object-file3" -5") at the
start, then the counter is incremented and when the productions create the
object files they simply make objectfile6-8, each with the default 0 BLA. I
don't think I can use setallbaselevels as the physical objects should not
have their activations changed because they are not part of the mental
representation.

I do need to come up with some kind of Lisp "shell" for this to present the
objects and different tasks, but not being much of a lisp hacker this would
be an unnecessary barrier to getting the model finished and submitted for
publication soon. So, is there any simple solution to this problem? Thanks
--Tony Simon

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Tony J. Simon
Assistant Professor of Psychology & Cognitive Science
School of Psychology                                    (Tel) (404) 894-2681
Georgia Institute of Technology                         (FAX) (404) 894-8905
Atlanta, GA 30332-0170          Internet: tony.simon at psych.gatech.edu
WWW page  http://www.prism.gatech.edu/~as53/
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