Hello,
I'm trying to create a dot probe task in which each stimulus pair is presented once in each of four trial types (based on top-bottom or bottom-top configuration of each word pair, and the location of the probe).
I thought the script was working fine, but have discovered that the stimulus pairs are not always presented in the correct pairs (e.g. 3/16 pairs are not matched in a basic version with only four stimulus pairs).
The script is below:
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ITEMS
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<item target>
/1 = "one"
/2 = "two"
/3 = "three"
/4 = "four"
</item>
<item neutral>
/ 1 = "ONE"
/ 2 = "TWO"
/ 3 = "THREE"
/ 4 = "FOUR"
</item>
<item probe>
/1 = "p"
/2 = "q"
</item>
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TEXT AND COUNTERS
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<text probe>
/ items = probe
/ select = replace
/ color = white
/ vposition = probevpos
</text>
<text target>
/items = target
/select = stimcounter
/vposition = threatvpos
</text>
<text neutral>
/items = neutral
/select = current(stimcounter)
/vposition = neutralvpos
</text>
<counter stimcounter>
/ items =
(1,1,1,1,
2,2,2,2,
3,3,3,3,
4,4,4,4)
/ select = noreplacenorepeat
</counter>
<counter threatvpos>
/ items =
(47%,53%,47%,53%,
47%,53%,47%,53%,
47%,53%,47%,53%,
47%,53%,47%,53%)
/ select = current(stimcounter)
</counter>
<counter neutralvpos>
/items =
(53%, 47%, 53%, 47%
53%, 47%, 53%, 47%
53%, 47%, 53%, 47%
53%, 47%, 53%, 47%)
/select = current(stimcounter)
</counter>
<counter probevpos>
/items =
(47%, 47%, 53%, 53%,
47%, 47%, 53%, 53%,
47%, 47%, 53%, 53%,
47%, 47%, 53%, 53%)
/select = current(stimcounter)
</counter>
<counter correctresponse>
/ items = (25, 16)
/ select = current(probe)
</counter>
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OTHER STIMULI AND DEFAULTS
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<text fixation>
/items = (" + ")
/ fontstyle = ("Times", 24pt)
</text>
<shape erase>
/ color = (150,150,150)
/ size = (100%, 100%)
</shape>
<defaults>
/ txbgcolor = transparent
/ screencolor = (150,150,150)
/ txcolor = white
/ fontstyle = ("Arial Rounded MT", 14pt)
</defaults>
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TRIALS AND BLOCKS
*******************************************************************
<trial maintrial>
/stimulustimes = [0 = fixation; 500 = erase, target, neutral; 1000 = erase, probe]
/inputdevice = keyboard
/validresponse = ("p","q")
/iscorrectresponse = [trial.maintrial.response==counter.correctresponse.selectedvalue]
/responsetime = 1000
/timeout = 2500
</trial>
<block main>
/trials = [1-16 = maintrial]
</block>
Many thanks!