Millisecond Forums » Millisecond Forums » Inquisit 3 » Stroop Task balancing/ordering

Stroop Task balancing/ordering

zzril — Wed, 26 Sep 2012 09:53:31 GMT

I am creating a Stroop Task and would like to balance the presentation of stimuli such that there are equal number of congruent and incongruent trials. Additionally, I'd like to be able to display each of the four colors an equal number of times and randomly order the presentation so that combinations which have been presented previously will have a lower probability of being presented again. In lieu of this, is there any way to prevent identical stimuli from being presented consecutively? Any assistance would be greatly appreciated.

RE: Stroop Task balancing/ordering

Dave — Wed, 26 Sep 2012 09:53:31 GMT

'noreplacenorepeat' merely means that the respective counter will not select the same value twice in a row (if possible). I.e., not something like ... - 2 - 2 - ...

The counters contain 24 values. I.e., across 48 they'll be selected twice (once in the 1st set of 24 trials, the 2nd for the remaining set of trials 25-48).

12 items in your counter map to "XXXX". Thus, simple math reveals that, yes, the end result should be 24 trials including "XXXX". However, why don't you just try this for yourself? Generate some data and have your preferred stats or spreadsheet application count the occurences for you.

RE: Stroop Task balancing/ordering

zzril — Wed, 26 Sep 2012 09:44:55 GMT

Since the following counter specifies a noreplacenorepeat, shouldn't I get six trials of each color word and 24 trials of the XXXX word in an experiment with 48 trials?:

RE: Stroop Task balancing/ordering

Dave — Mon, 17 Sep 2012 15:18:47 GMT

No, there isn't.

RE: Stroop Task balancing/ordering

zzril — Mon, 17 Sep 2012 15:17:02 GMT

Is there a way to simultaneously run

/ inputdevice = voice
/ inputdevice = voicerecord

RE: Stroop Task balancing/ordering

Dave — Mon, 17 Sep 2012 11:45:05 GMT

Here are some errors when trying to parse the script you attached:

<trial ICtrial>
/validresponse: 'No response' can not be specified unless the trial has a timeout.
[...]
<trial practicetrial>
/validresponse: 'No response' can not be specified unless the trial has a timeout.
<trial XXtrial>
/validresponse: 'No response' can not be specified unless the trial has a timeout.
[...]

You have not defined any valid responses for the respective trial elements. E.g.:

<trial ICtrial>
/ ontrialbegin = [values.stimcolor=counter.cdic.selectedvalue]
/ ontrialbegin = [text.stimword.textcolor=getitem(counter.stimcolor, values.stimcolor)]
/ ontrialbegin = [values.stimword=getitem(item.colorwords, counter.cwic.selectedvalue)]
/ stimulustimes = [0=fixation;250=stimword]
</trial>

Thus Inquisit must assume you allow no response. But since the trial does not /timeout in any way, it would effectively go on forever.

RE: Stroop Task balancing/ordering

Dave — Mon, 17 Sep 2012 11:20:45 GMT

[quote]I understand that it's attempting to select a first and a last name for eight trials, though it would be difficult to know for sure since both scripts crash when I run them.[/quote]

This suggests you are either running an outdated Inquisit version (in which case: re-download and re-install) or there is something wrong with your system in general (not sure what you would want to do in this case). I have pointed out the issues in your script in my previous replies, none of which should lead to crashing.

RE: Stroop Task balancing/ordering

zzril — Mon, 17 Sep 2012 11:15:47 GMT

I understand that it's attempting to select a first and a last name for eight trials, though it would be difficult to know for sure since both scripts crash when I run them.

I appreciate your attempts at assisting me in learning this software through examples, but it would be much more helpful if you could identify the specific issues with my script. The monkey also crashes the program when I run it, so I don't know where it's breaking down.

RE: Stroop Task balancing/ordering

Dave — Thu, 13 Sep 2012 15:10:27 GMT

Consider this:

<counter firstname>
/ items = ("John", "Paul", "George", "Ringo")
/ select = noreplacenorepeat
</counter>

<counter lastname>
/ items = ("Lennon", "McCartney", "Harrison", "Starr", "Ono")
/ select = current(firstname)
</counter>

<trial showbeatles>
/ stimulusframes = [1=thename]
/ validresponse = (57)
</trial>

<text thename>
/ items = ("<%counter.firstname.selectedvalue%> <%counter.lastname.selectedvalue%>")
</text>

<block wheresyoko>
/ trials = [1-8=showbeatles]
</block>

Ask yourself: Will you see the last name "Ono" when running the code? Why or why not?

What will the following code produce as output:

<counter firstname>
/ items = ("John", "Paul", "George", "Ringo")
/ select = noreplace
</counter>

<counter lastname>
/ items = ("Lennon", "McCartney", "Harrison", "Starr", "Ono")
/ select = noreplace
</counter>

<trial showbeatles>
/ stimulusframes = [1=thename]
/ validresponse = (57)
</trial>

<text thename>
/ items = ("<%counter.firstname.selectedvalue%> <%counter.lastname.selectedvalue%>")
</text>

<block wheresyoko>
/ trials = [1-8=showbeatles]
</block>

What would you have to do to display every possible combination of first and last name? Apply this to your own script.

RE: Stroop Task balancing/ordering

zzril — Thu, 13 Sep 2012 15:04:04 GMT

Thanks, but this isn't helpful. The documentation is sparse at best and the tutorials don't apply to the script I'm trying to write. Searches for counter dependencies and variations of that string return forum posts which are only marginally relevant.

RE: Stroop Task balancing/ordering

Dave — Tue, 11 Sep 2012 13:09:06 GMT

One issue is the same as noted previously: You counter dependencies are off:

<counter cdxx>
/ items = (2,3,4,5,1,3,4,5,1,2,4,5,1,2,3,5,1,2,3,4)
/ select = noreplacenorepeat
/ selectionrate = trial
</counter>

*******************
*******************
*Word
*******************
*******************

<counter cwxx>
/ items = (1,1,1,1,1,2,2,2,2,2,3,3,3,3,3,4,4,4,4,4,5,5,5,5,5)
/ select = current(cdxx)
/ selectionrate = trial
</counter>

The 1st counter holds 20 items, the 2nd counter holds 25. Obviously the last 5 listed cannot ever be selected. I recommed that -- before you go about changing / adapting an existing script - you work through the original script until you fully understand what it does, how it works and why.

Best regards,

~Dave

RE: Stroop Task balancing/ordering

zzril — Tue, 11 Sep 2012 12:41:35 GMT

So I'm still having no luck getting the XXXX text to display. I've taken the syntax for the Food Stroop and just replaced the congruent color trial with an XXXX trial and it crashes every time. I didn't change the counter values at all, so don't really know what I'm doing wrong.

*******************************************************************************************************
*******************************************************************************************************
VOICE RECOGNITION FOUR COLOR STROOP TASK
*******************************************************************************************************
*******************************************************************************************************

*******************************************************
*******************************************************
*DEFAULTS
*******************************************************
*******************************************************

<defaults>
/ fontstyle = ("Verdana", 6.00%, true)
/ screencolor = (white)
/ txbgcolor = (white)
/ inputdevice = voicerecord
/ voicekeythreshold = 50
/ posttrialpause = 500
</defaults>

*******************************************************
*******************************************************
*Values
*******************************************************
*******************************************************

*Notes:
*'values.stimcolor' contains a numeric representation of the current word's display color:
*1=blue, 2=green, 3=red, 4=yellow
*'values.condition' contains a numeric representation of the current condition:
*1=incongruent, 2=XXXX

<values>
/ stimcolor = 0
/ stimword = ""
/ condition = 0
</values>

*******************************************************
*******************************************************
*Custom Data Output
*******************************************************
*******************************************************
<data>
/ columns = [date,time,subject,blocknum,blockcode,trialnum,trialcode,latency,response,
    values.stimword,values.stimcolor,values.condition]
/ separatefiles = true
</data>

*******************************************************
*******************************************************
*TRIALS
*******************************************************
*******************************************************

*****************
*****************
*Instruction Trial
*****************
*****************

<trial instructiontrial>
/ stimulustimes = [0=instructions, navigation;500=example01,example02 ]
/ inputdevice = keyboard
/ validresponse = (57)
/ recorddata = false
</trial>

*****************
*****************
*Practice Trial
*****************
*****************

<trial practicetrial>
/ ontrialbegin = [values.stimcolor=counter.practicecolors.selectedvalue]
/ ontrialbegin = [text.stimword.textcolor=getitem(counter.stimcolor,values.stimcolor)]
/ ontrialbegin = [values.stimword=counter.practicewords.selectedvalue]
/ stimulustimes = [0=fixation;250=stimword]
</trial>

*****************
*Color trials
*****************
*Incongruent

<trial ICtrial>
/ ontrialbegin = [values.stimcolor=counter.cdic.selectedvalue]
/ ontrialbegin = [text.stimword.textcolor=getitem(counter.stimcolor, values.stimcolor)]
/ ontrialbegin = [values.stimword=getitem(item.colorwords, counter.cwic.selectedvalue)]
/ stimulustimes = [0=fixation;250=stimword]
</trial>

*XXXX

<trial XXtrial>
/ ontrialbegin = [values.stimcolor=counter.cdic.selectedvalue]
/ ontrialbegin = [text.stimword.textcolor=getitem(counter.stimcolor, values.stimcolor)]
/ ontrialbegin = [values.stimword=getitem(item.colorwords, counter.cwxx.selectedvalue)]
/ stimulustimes = [0=fixation;250=stimword]
</trial>

*******************************************************
*******************************************************
*BLOCKS
*******************************************************
*******************************************************
<block practiceblock>
/ trials = [1-5=practicetrial]
</block>

<block instructions01>
/ bgstim = (whitebg)
/ trials = [1-3=instructiontrial]
</block>

<block instructions02>
/ bgstim = (whitebg)
/ trials = [1=instructiontrial]
</block>

<block instructions03>
/ bgstim = (whitebg)
/ trials = [1=instructiontrial]
</block>

<block IC>
/ onblockbegin = [values.condition=1]
/ trials = [1-20=ICtrial]
</block>

<block XX>
/ onblockbegin = [values.condition=2]
/ trials = [1-20=XXtrial]
</block>

*******************************************************
EXPERIMENT
*******************************************************

<expt stroop>
/ blocks = [1=instructions01; 2=practiceblock; 3=instructions02;
    4-5=noreplacenorepeat(IC, XX);
    6=instructions03]
</expt>

*******************************************************
*******************************************************
*Stimulus Elements
*******************************************************
*******************************************************

<text stimword>
/ items = ("<%values.stimword%>")
/ txcolor = (white)
</text>

<text fixation>
/ items = ("+")
/ txcolor = (black)
</text>

<shape whitebg>
/ shape = rectangle
/ color = white
/ erase = false
/ size = (87.5%, 87.5%)
</shape>

*******************************************************
*******************************************************
Counter Elements / Selection Logic
*******************************************************
*******************************************************
*Practice Items
*******************
*******************

<counter practicewords>
/ items = ("GREEN", "RED", "BLUE", "YELLOW", "XXXX")
/ select = current(practicecolors)
</counter>

<counter practicecolors>
/ items = (3,4,5,1,2)
/ select = sequence
</counter>

*******************
*******************
*Counter Elements / Selection Logic for Test Block
*******************
*******************

<counter stimcolor>
/ items = (blue, green, red, yellow)
/ select = values.stimcolor
</counter>

*******************************************************
*******************************************************

*******************
*******************
*Incongruent Color (IC)
*******************
*******************
*Display
*******************
*******************

<counter cdic>
/ items = (2,3,4,5,1,3,4,5,1,2,4,5,1,2,3,5,1,2,3,4)
/ select = noreplacenorepeat
/ selectionrate = trial
</counter>

*******************
*******************
*Word
*******************
*******************

<counter cwic>
/ items = (1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4,5,5,5,5)
/ select = current(cdic)
/ selectionrate = trial
</counter>

*******************
*******************
*XXXX (XX)
*******************
*******************
*Display
*******************
*******************

<counter cdxx>
/ items = (2,3,4,5,1,3,4,5,1,2,4,5,1,2,3,5,1,2,3,4)
/ select = noreplacenorepeat
/ selectionrate = trial
</counter>

*******************
*******************
*Word
*******************
*******************

<counter cwxx>
/ items = (1,1,1,1,1,2,2,2,2,2,3,3,3,3,3,4,4,4,4,4,5,5,5,5,5)
/ select = current(cdxx)
/ selectionrate = trial
</counter>

*******************************************************
*******************************************************
*Items: Color Words
*******************************************************
*******************************************************

<item colorwords>
/1 ="         RED         "
/2 ="        GREEN        "
/3 ="        BLUE         "
/4 ="       YELLOW        "
/5="         XXXX         "
</item>

*******************************************************
*******************************************************
*INSTRUCTIONS
*******************************************************
*******************************************************

<text instructions>
/ items = instructions
/ select = sequence
/ size = (85%, 85%)
/ txbgcolor = (transparent)
/ fontstyle = ("Verdana", 3.00%, true)
/ erase = false
/ resetinterval = 0
</text>

<item instructions>
/ 1 = "~rYou will see a series of words displayed in different colors.
Name aloud the color of the presented word
- red, yellow, green, blue, or black -
as quickly and as accurately as possible.
If you make a mistake, keep going."
/ 2 = "~rYou will see a series of words displayed in different colors.
Name aloud the color of the presented word
- red, yellow, green, blue, or black -
as quickly and as accurately as possible.
If you make a mistake, keep going.~r
For example, when this word appears,~r~r~r
you would respond with ''red'' as quickly as possible."
/ 3 = "~rYou will see a series of words displayed in different colors.
Name aloud the color of the presented word
- red, yellow, green, blue, or black -
as quickly and as accurately as possible.
If you make a mistake, keep going.~r
For example, when this word appears,~r~r~r
you would respond with ''red'' as quickly as possible.~r
If this word appears,~r~r~r
you would respond with ''blue'' as quickly as possible. ~r
Let's practice a few words before we begin."
/ 4 = "~r~r~r~r~r~rIf you have any questions, please ask the study coordinator now.~r
When you are ready to begin, press the SPACE BAR."
/ 5 = "~r~r~r~r~r~rPlease let the study coordinator know you have finished."
</item>

<text example01>
/ items = example01
/ select = sequence
/ resetinterval = 0
/ txcolor = (red)
/ txbgcolor = (transparent)
/ position = (50%, 41%)
/ erase = false
</text>

<item example01>
/ 1 = " "
/ 2 = "YELLOW"
/ 3 = "YELLOW"
/ 4 = " "
</item>

<text example02>
/ items = example02
/ select = sequence
/ resetinterval = 0
/ position = (50%, 63%)
/ txcolor = (blue)
/ txbgcolor = (transparent)
/ erase = false
</text>

<item example02>
/ 1 = " "
/ 2 = " "
/ 3 = "GREEN"
/ 4 = " "
/ 5 = " "
</item>

<text navigation>
/ items = navigation
/ select = sequence
/ resetinterval = 0
/ fontstyle = ("Verdana", 3.00%, true)
/ txbgcolor = (white)
/ size = (87.5%, 5%)
/ position = (50%, 90%)
/ erase = false
</text>

<item navigation>
/ 1 = "Press the SPACEBAR to continue."
/ 2 = "Press the SPACEBAR to continue."
/ 3 = "Press the SPACE BAR when you are ready to begin."
/ 4 = " "
/ 5 = " "
</item>

RE: Stroop Task balancing/ordering

Dave — Mon, 10 Sep 2012 15:42:18 GMT

I recommend you

Take out paper and pencil. Make a table.
In the 1st column, write down the display color of the stimulus.
In the 2nd column, write down the stimulus word.
Repeat until you have all desired combinations listed in the desired amount.
Encode those combinations in <counter> elements. You need one per column.

-----------------------------------
       Congruent Trials
-----------------------------------
[#] [Display Color] [Stimulus Word]
-----------------------------------
1   BLUE            BLUE
2   GREEN           GREEN
3   RED             RED
4   YELLOW          YELLOW
5   BLUE            BLUE
6   GREEN           GREEN
7   RED             RED
...

-----------------------------------
      Incongruent Trials
-----------------------------------
[#] [Display Color] [Stimulus Word]
-----------------------------------
1   BLUE            GREEN
2   BLUE            RED
3   BLUE            YELLOW
4   GREEN           BLUE
5   GREEN           RED
6   GREEN           YELLOW
...

Etc.

Regards,

~Dave

RE: Stroop Task balancing/ordering

zzril — Mon, 10 Sep 2012 15:37:06 GMT

The counter is what is confusing me and I'm still unclear how to get it to display "XXXX" in each of the colors.

RE: Stroop Task balancing/ordering

Dave — Mon, 10 Sep 2012 15:04:21 GMT

Looking only at the two dependent counters below,

<counter cdcc>
/ items = (1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4)
/ select = noreplacenorepeat
/ selectionrate = trial
</counter>

<counter cwcc>
/ items = (1,1,1,1,1,2,2,2,2,2,3,3,3,3,3,4,4,4,4,4,5,5,5,5,5)
/ select = current(cdcc)
/ selectionrate = trial
</counter>

it should be obvious that things won't work. They contain different numbers of items (16 in cdcc, 25 in cwcc).

I recommend you give the threads I referred you to earlier another look. EDIT: My bad. I hadn't mentioned any other thread. Here goes, my apologies:

E.g. http://www.millisecond.com/forums/Topic2270.aspx

Regards,

~Dave

RE: Stroop Task balancing/ordering

zzril — Mon, 10 Sep 2012 14:45:58 GMT

So I was able to adapt the Food Stroop, but still am unable to get it to balance my congruent and incongruent trials. I know it has something to do with the noreplace statement, but I'm not savvy enough to use it correctly. I also wanted to present a series of XXXX instead of a color word as a neutral stimulus, but can't seem to get it to display. On my test run of 20 trials, I'm getting the following patterns:

RED = 1 congruent color, 5 incongruent color

YELLOW = 1 cc, 0 ic

GREEN = 3 cc, 4 ic

BLUE = 0 cc, 6 ic

XXXX = nothing

I know there must be something that is glaringly obvious, but I'm not seeing it. Here's the script:

*******************************************************************************************************
*******************************************************************************************************
VOICE RECOGNITION FOUR COLOR STROOP TASK
*******************************************************************************************************
*******************************************************************************************************

*******************************************************
DEFAULTS
*******************************************************

<defaults>
/ fontstyle = ("Verdana", 6.00%, true)
/ screencolor = (white)
/ txbgcolor = (white)
/ inputdevice = voicerecord
/ voicekeythreshold = 50
/ posttrialpause = 500
</defaults>

*******************************************************
*******************************************************
*Values
*******************************************************
*******************************************************

*Notes:
*'values.stimcolor' contains a numeric representation of the current word's display color:
*1=blue, 2=green, 3=red, 4=yellow
*'values.condition' contains a numeric representation of the current condition:
*1=congruent, 2=incongruent

<values>
/ stimcolor = 0
/ stimword = ""
/ condition = 0
</values>

*******************************************************
TRIALS
*******************************************************

*****************
*****************
*Instruction Trial
*****************
*****************

<trial instructiontrial>
/ stimulustimes = [0=instructions, navigation;500=example01,example02 ]
/ inputdevice = keyboard
/ validresponse = (57)
/ recorddata = false
</trial>

*****************
*****************
*Practice Trial
*****************
*****************

<trial practicetrial>
/ ontrialbegin = [values.stimcolor=counter.practicecolors.selectedvalue]
/ ontrialbegin = [text.stimword.textcolor=getitem(counter.stimcolor,values.stimcolor)]
/ ontrialbegin = [values.stimword=counter.practicewords.selectedvalue]
/ stimulustimes = [0=fixation;200=stimword]
</trial>

*****************
*Color trials
*****************
*Congruent

<trial CCtrial>
/ ontrialbegin = [values.stimcolor=counter.cdcc.selectedvalue]
/ ontrialbegin = [text.stimword.textcolor=getitem(counter.stimcolor, values.stimcolor)]
/ ontrialbegin = [values.stimword=getitem(item.colorwords, counter.cwcc.selectedvalue)]
/ stimulustimes = [0=fixation;200=stimword]
</trial>

*Incongruent

<trial ICtrial>
/ ontrialbegin = [values.stimcolor=counter.cdic.selectedvalue]
/ ontrialbegin = [text.stimword.textcolor=getitem(counter.stimcolor, values.stimcolor)]
/ ontrialbegin = [values.stimword=getitem(item.colorwords, counter.cwic.selectedvalue)]
/ stimulustimes = [0=fixation;200=stimword]
</trial>

*******************************************************
BLOCKS
*******************************************************
<block practiceblock>
/ trials = [1-5=practicetrial]
</block>

<block instructions01>
/ bgstim = (whitebg)
/ trials = [1-3=instructiontrial]
</block>

<block instructions02>
/ bgstim = (whitebg)
/ trials = [1=instructiontrial]
</block>

<block instructions03>
/ bgstim = (whitebg)
/ trials = [1=instructiontrial]
</block>

<block CC>
/ onblockbegin = [values.condition=1]
/ trials = [1-10=CCtrial]
</block>

<block IC>
/ onblockbegin = [values.condition=2]
/ trials = [1-10=ICtrial]
</block>

*******************************************************
EXPERIMENT
*******************************************************

<expt stroop>
/ blocks = [1=instructions01; 2=practiceblock; 3=instructions02;
    4-5=noreplacenorepeat(CC,IC);
    6=instructions03]
</expt>

*******************************************************
*******************************************************
*Stimulus Elements
*******************************************************
*******************************************************

<text stimword>
/ items = ("<%values.stimword%>")
/ txcolor = (white)
</text>

<text fixation>
/ items = ("+")
/ txcolor = (black)
</text>

<shape whitebg>
/ shape = rectangle
/ color = white
/ erase = false
/ size = (87.5%, 87.5%)
</shape>

*******************************************************
*******************************************************
Counter Elements / Selection Logic
*******************************************************
*******************************************************
*Practice Items
*******************
*******************
<counter practicewords>
/ items = ("GREEN", "RED", "BLUE", "YELLOW", "XXXX")
/ select = current(practicecolors)
</counter>

<counter practicecolors>
/ items = (3,4,1,2)
/ select = sequence
</counter>

*******************
*******************
*Counter Elements / Selection Logic for Test Block
*******************
*******************
<counter stimcolor>
/ items = (blue, green, red, yellow)
/ select = values.stimcolor
</counter>

*******************************************************
*******************************************************
*Congruent Color (CC)
*******************
*******************
*Display
*******************
*******************
<counter cdcc>
/ items = (1,1,1,1,2,2,2,2,3,3,3,3,4,4,4,4)
/ select = noreplacenorepeat
/ selectionrate = trial
</counter>

*******************
*******************
*Word
*******************
*******************

<counter cwcc>
/ items = (1,1,1,1,1,2,2,2,2,2,3,3,3,3,3,4,4,4,4,4,5,5,5,5,5)
/ select = current(cdcc)
/ selectionrate = trial
</counter>

*******************
*******************
*Incongruent Color (IC)
*******************
*******************
*Display
*******************
*******************

<counter cdic>
/ items = (2,3,4,1,3,4,1,2,4,1,2,3,1,2,3,4)
/ select = noreplacenorepeat
/ selectionrate = trial
</counter>

*******************
*******************
*Word
*******************
*******************

<counter cwic>
/ items = (1,1,1,1,1,2,2,2,2,2,3,3,3,3,3,4,4,4,4,4,5,5,5,5,5)
/ select = current(cdic)
/ selectionrate = trial
</counter>

*******************
*******************

<item colorwords>
/1 ="         RED         "
/2 ="        GREEN        "
/3 ="        BLUE         "
/4 ="       YELLOW        "
/5="         XXXX         "
</item>

*******************

*******************************************************
INSTRUCTIONS
*******************************************************

<text instructions>
/ items = instructions
/ select = sequence
/ size = (85%, 85%)
/ txbgcolor = (transparent)
/ fontstyle = ("Verdana", 3.00%, true)
/ erase = false
/ resetinterval = 0
</text>

<item instructions>
/ 1 = "~rYou will see a series of words displayed in different colors.
Name aloud the color of the presented word
- red, yellow, green, blue -
as quickly and as accurately as possible.
If you make a mistake, keep going."
/ 2 = "~rYou will see a series of words displayed in different colors.
Name aloud the color of the presented word
- red, yellow, green, blue -
as quickly and as accurately as possible.
If you make a mistake, keep going.~r
For example, when this word appears,~r~r~r
you would respond with ''red'' as quickly as possible."
/ 3 = "~rYou will see a series of words displayed in different colors.
Name aloud the color of the presented word
- red, yellow, green, blue -
as quickly and as accurately as possible.
If you make a mistake, keep going.~r
For example, when this word appears,~r~r~r
you would respond with ''red'' as quickly as possible.~r
If this word appears,~r~r~r
you would respond with ''blue'' as quickly as possible. ~r
Let's practice a few words before we begin."
/ 4 = "~r~r~r~r~r~rIf you have any questions, please ask the study coordinator.~r
When you are ready to begin, press the SPACE BAR."
/ 5 = "~r~r~r~r~r~rPlease let the study coordinator know you have finished."
</item>

<text example01>
/ items = example01
/ select = sequence
/ resetinterval = 0
/ txcolor = (red)
/ txbgcolor = (transparent)
/ position = (50%, 41%)
/ erase = false
</text>

<item example01>
/ 1 = " "
/ 2 = "YELLOW"
/ 3 = "YELLOW"
/ 4 = " "
</item>

<text example02>
/ items = example02
/ select = sequence
/ resetinterval = 0
/ position = (50%, 63%)
/ txcolor = (blue)
/ txbgcolor = (transparent)
/ erase = false
</text>

<item example02>
/ 1 = " "
/ 2 = " "
/ 3 = "GREEN"
/ 4 = " "
/ 5 = " "
</item>

<text navigation>
/ items = navigation
/ select = sequence
/ resetinterval = 0
/ fontstyle = ("Verdana", 3.00%, true)
/ txbgcolor = (white)
/ size = (87.5%, 5%)
/ position = (50%, 90%)
/ erase = false
</text>

<item navigation>
/ 1 = "Press the SPACEBAR to continue."
/ 2 = "Press the SPACEBAR to continue."
/ 3 = "Press the SPACE BAR when you are ready to begin."
/ 4 = " "
/ 5 = " "
</item>

RE: Stroop Task balancing/ordering

Dave — Thu, 06 Sep 2012 10:10:45 GMT

[quote] is there any way to prevent identical stimuli from being presented consecutivel[/quote]

See the documentation for the replacenorepeat and noreplacenorepeat selection modes.

[quote]I am creating a Stroop Task and would like to balance the presentation of stimuli such that there are equal number of congruent and incongruent trials. Additionally, I'd like to be able to display each of the four colors an equal number of times and randomly order the presentation so that combinations which have been presented previously will have a lower probability of being presented again.[/quote]

See e.g. the Food Stroop script available from the Task Library for a possible approach. In short, you'll want to set up elements encoding your stimulus / feature combinations and sample from those combinations.

Regards,
~Dave