[ACT-R-users] Novice experiment code problem

[James Grange]

Hi all,

Apologies for the novice question.

I am adapting the experiment code of tutorial 4's assignment (the Zbrodoff
experiment) to be a simple flanker task. I have only slightly modified the
code from the Zbrodoff, but I am running in to an error that I can't find
location of the faulty code (code attached).

When I run the do-trial function [i.e. (do-trial "a" "b" "incongruent" "z"
t) ], I get the following error:

Error: Non-structure argument NIL passed to ref of structure slot 1
[condition type: SIMPLE-ERROR]

It seems that NIL is being passed to the present-trial function, but
nothing should be passed to this function as *TRIALS* should be empty, as
it should have been cleared during (defmethod
rpm-window-key-event-handler).

As you can see from the code, I have commented out all the higher level
code at this point as I am just trying to get the code to present a single
trial.

Any help gratefully received.

Best wishes,

Jim Grange.
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