n-back

[Nolan, Karen]

Hi Nick - The nback program I'm running uses the following
'Make sure that the letter to be presented is not accidentally a
'two-back match.  If it is, select a different letter to present.
IF c.GetAttrib("Stimnum") = TwoLettersBack then
if val(c.GetAttrib("Stimnum"))<4 then
 c.SetAttrib "Stimnum", (val(c.GetAttrib("Stimnum"))+1)
 else c.SetAttrib "Stimnum", (val(c.GetAttrib("Stimnum"))-1)
end if


else


'Set TwoLettersBack to what was previously OneLetterBack.
'Set OneLetterBack to the current letter.
TwoLettersBack = OneLetterBack
OneLetterBack = c.GetAttrib("Stimnum")
end if

It looks pretty similar to what you're using.

The inline in my match procedure looks like this:
c.SetAttrib "Stimnum", TwoLettersBack


'Set TwoLettersBack to what was previously OneLetterBack.
'Set OneLetterBack to the current letter.
TwoLettersBack = OneLetterBack
OneLetterBack = c.GetAttrib("Stimnum")

Have you checked your match procedure to be sure that those trials have the
same attributes as the no match trials?

Karen Nolan

-----Original Message-----
From: Nick Coupland [mailto:nc2 at ualberta.ca]
Sent: Friday, May 07, 2004 1:38 PM
To: eprime at mail.talkbank.org
Subject: n-back

Hi, I'm trying to get up a two back task with a randomized letter list,
which takes from one of two trial lists :-
no match        TwoNoMTrialList
match           TwoMTrialList



The no match procedure has an inline script to modify the letter if it is an
accidental match to the two back letter:


'Add contents of TwoList to the "context" in which we are working.
c.Add TwoList
c.Update


'Declare a variable, i, for use as a counter in a while-loop
Dim i As Integer
i = 0


'Make sure that the letter to be presented is not accidentally a
'two-back match.  If it is, select a different letter to present.
While c.GetAttrib("Letters") = TwoLettersBack
        c.SetAttrib "Letters", TwoNoMTrialList.GetAttrib(i, "Letters")
        i = i + 1
Wend


'Set TwoLettersBack to what was previously OneLetterBack.
'Set OneLetterBack to the current letter.
TwoLettersBack = OneLetterBack
OneLetterBack = TwoNoMTrialList.GetCurrentAttrib("Letters")


However, this only works when the two back letter is from a no match trial.
If it is from a match trial, it crashes. How do I modify the script so it
can recognize accidental matches from both match and no match trials?
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