Alternative to response counters for selection from lists with fixed reward/loss?

[KKat]

Dear members:

I posted a few weeks ago with regard to a modified version of the Iowa
Gambling Task that I was working on and I received great initial
advice from a fellow member on how to use nested lists to achieve my
goal of selecting from four different lists on each trial. However, I
now have another problem, so here it goes....

Currently, I have a List object (named DesignList) which consists of
one row and the following under the Nested column: DeckA, DeckB,
DeckC, Deck D.

It looks like this:

ID    Weight     Procedure
Nested                                    Attributes.....
---------------------------------------------------------------------------------------------------------------------------------
1         1          TrialProc     DeckA,DeckB,DeckC,DeckD

Then, I have four separate lists (DeckA, DeckB, DeckC, DeckD) created
under the DesignList.
Each of these lists has the same structure, which looks like this:

DeckA:

ID    Weight     varwin1      varloss1
---------------------------------------------------------------------------------------------------------------------------------
1         1          +100            0
2         1          +100            0
3         1          +100            -150
etc.


DeckB:
ID    Weight     varwin2      varloss2
---------------------------------------------------------------------------------------------------------------------------------
1         1          +100            0
:          1          +100            0
10        1          +100         -1250
etc.

I am able to sample each list (i.e., the program is selecting from the
correct list and all lists work) and the task works ok as it's coded.
However, it's not doing what I need it to do. In this task, it is
imperative that the
losses/rewards in each deck are presented in a specific, non-random
order so that the experimenter can assess for sensitivity to reward
and punishment, as well as reinforcement learning.

Although the sampling is set to "sequential" for each list, it does
not start on ID_1 for each deck --- for example, if I start selecting
from DeckA and then move to DeckB for the second trial, it selects the
[varwin2] and
[varloss2] values from row ID_2; if I then select DeckD, it selects
the [varwin4] and [varloss4] from row ID_3.

I would like the sampling for each deck to be independent from the
others - the program should refer to row ID_1, then ID_2, then ID_3
and so forth from EACH deck. In other words, the wins/losses should be
fixed (i.e., if any participant chooses DeckX for the third time, they
will all win/lose the same amount).

I have been informed that when using nested lists, e-prime can only
select one level from each list for each trial and  cannot select one
of the lists based on the answer given. This means that for trial 1
the four first levels of the four deck-lists are all four loaded by e-
prime and based on the answer one of them is 'shown' to the subject.
Because all four first levels are loaded e-prime will load the four
second levels for the next trial etc. This means that a level for, for
instance, deck B is 'used' whether or not the subject chooses this
deck.

Instead, it was suggested to me that I should delete the lists and
code the wins/losses using response counters. My understanding is that
I would would need to declare variables that count each response given
(for instance 'respbcounter' counts how  often the response is b).
Then, based on the respbcounter, the win/loss is
 determined for a trial (if respbcounter is 8 then varwin2  = +100 and
varloss2 = -0;  if respbcounter is 9 then varwin2 = +100 and varloss2
= -1250). I would have to do the same for the three other decks.

I have never used response counters or nested lists before this task -
can anyone confirm whether or not response counters will solve my
problem?? Or, does anyone have any other suggestions?
Thank you!
Kathy
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