[ACT-R-users] Novice experiment code problem

[Dan Bothell]

--On Saturday, November 19, 2011 1:20 PM +0000 James Grange <j.a.grange at psy.keele.ac.uk> wrote:

> 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.
>


While I can't really debug your Lisp code for you since I don't know
exactly what it or the model is supposed to do, I can tell you where
the error is occurring when I run the do-trial function like you
show, and that may help you fix it.

The error happens in the rpm-window-key-event-handler method when
*trials* is already empty.  Thus, trial is set to nil and it is
the call to (trial-block trial) which actually throws the error.

I don't know if that's a problem with the model pressing keys when you
weren't expecting it to or if there's something wrong with the
experiment code, but hopefully that'll help you to fix it.

Dan