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Random stimuls selection in trial

SzymonUchacz — Tue, 16 Aug 2016 05:39:42 GMT

Hello!
I am creating an experiment using a dual-stream version of RSVP paradigm. The task is to identify the T1 and T2 targets that are preceded and followed by distractors.
The script for the distractors looks like this:

<item DYS>
/1="Q"/2="W"/3="E" /4="R" /5="T" /6="Y" /7="U"
/8="I" /9="O" /10="P" /11="A" /12="S" /13="H"
/14="Z" /15="X" /16="C" /17="V" /18="B" /19="N" /20="M"
</item>

<text DYSL>
/ items = DYS
/ position = (25,50)
/ fontstyle = ("Helvetica", 6.38%, true, false, false, false, 5, 1)
/ select = noreplace

</text>
<text DYSR>
/ items = DYS
/ position = (75,50)
/ fontstyle = ("Helvetica", 6.38%, true, false, false, false, 5, 1)
/ select = noreplace
</text>

And the script for the first trial looks like that:
<trial LAG1T1LT2L>
/ stimulustimes = [1= FIX, DYSL, DYSR;
130=FIX, DYSL, DYSR;
259=BLANK, BLANKL, BLANKR;
260=FIX, DYSL, DYSR;
289=BLANK, BLANKL, BLANKR;
390=FIX, DYSL, DYSR;
519=BLANK, BLANKL, BLANKR;
520=FIX, DYSL, DYSR;
649=BLANK, BLANKL, BLANKR;
650=FIX, DYSL, DYSR;
749=BLANK, BLANKL, BLANKR;
750=FIX, T1L, DYSR;
879=BLANK, BLANKL, BLANKR;
880=FIX, T2L, DYSR;
1009=BLANK, BLANKL, BLANKR;
1010=FIX, DYSL, DYSR;
1139=BLANK, BLANKL, BLANKR;
1140=FIX, DYSL, DYSR]

/ response = noresponse
</trial>
My problem is that when I run the script the first pair of distractors are being repeated for the whole trial, and I would want to get a random selection of items from the DYS directory on each stimulstimes involving distractors. How can I fix this problem?

Any help would be appreciated!

Thanks,
Szymon.

RE: Random stimuls selection in trial

SzymonUchacz — Tue, 16 Aug 2016 05:39:42 GMT

Thank you very much! It worked.

Szymon.

RE: Random stimuls selection in trial

Dave — Sun, 14 Aug 2016 18:16:12 GMT

That is by design. For a given stimulus element like <text a>, Inquisit will only allow for selection of ONE item per trial. I.e., if you present <text a> repeatedly in a <trial>, you'll always see the same item. What you need to do is have multiple stimulus elements, as in:

<block someblock>
/ trials = [1-10 = sometrial]
</block>

<trial sometrial>
/ ontrialbegin = [list.alist.reset(); ]
/ stimulustimes = [0=a1; 1000=a2; 2000=a3]
/ validresponse = (57)
</trial>

<text a1>
/ items = aitems
/ select = list.alist.nextindex
</text>

<text a2>
/ items = aitems
/ select = list.alist.nextindex
</text>

<text a3>
/ items = aitems
/ select = list.alist.nextindex
</text>

<item aitems>
/ 1 = "A_a"
/ 2 = "A_b"
/ 3 = "A_c"
/ 1 = "A_d"
/ 2 = "A_e"
/ 3 = "A_f"
</item>

<list alist>
/ poolsize = 6
/ selectionrate = always
</list>