Stop Signal ISI Randomization?

[Zach]

Hello All,
        This is my first time posting but as a new user of EPrime,
reading this list serve has been immensely helpful over the past month
and for that I thank you.

The problem I am currently grappling with is one of randomization. I
have a stop signal program that randomly (w/o replacement) presents
the user with 4 stimuli (goleft, goright, stopleft, and stopright),
with each stimulus presentation separated by inter-stimulus-interval
(blank screen). I have these 4 stimuli as separate procedures under a
List that weights each of the four differently (more go trials than
stop). In between each stimuli presentation I am attempting to
randomly (w/o replacement) select the ISI time from a weighted list
with five possible times (500ms, 750ms, etc).

My problem is that I cannot seem to get EPrime to randomly select both
without replacement in series. I need the program to run through
exactly the same amount of each stimulus (goL, goR etc) and the same
distribution of ISIs (500ms, 750ms etc) while randomly selecting and
pair both w/o replacement. I can get it to do one but not the other,
and was wondering if anyone knew a way to effectively place two lists
in a row, so that the program would choose randomly from one list and
then the other. Alternatively, would there be a way to have a list of
ISItimes that could be randomly accessed (w/o replacement) inside the
GoL GoR StopL StopR programs.

For example, the program would function as follows:
(P) TrialProcedure
     - (L) TrialList (with weighted GoL GoR etc.)
            - (P) GoL_procedure
		- (Slide) Fix
                        - (Slide) ArrowLeft
                        - (Slide) ISI   [and here the ISI time could
randomly access this magical list and select the time interval]
            - (P) GoR_procedure
END

I hope that my question isn't too long and that I explained everything
adequately. If anyone has any ideas I would greatly appreciate your
help.
Sincere Thanks,
         -Zach Cohen
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups "E-Prime" group.
To post to this group, send email to e-prime at googlegroups.com
To unsubscribe from this group, send email to e-prime+unsubscribe at googlegroups.com
For more options, visit this group at http://groups.google.com/group/e-prime?hl=en
-~----------~----~----~----~------~----~------~--~---