Visual Search Task - unwanted repetition of text/picture items and counterbalancing issues


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Dave
Dave
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Dave - 5/11/2020
Karolina K. - 5/10/2020
I exceeded the upload size in my first attempt and now I can not attach reduced and zipped image folder.

I don't understand what you want to do here.

What you would typically do is set up a trial for each condition and then sample those in equal proportions. For stimulus selection, you would use a single list so each item only occurs under a single condition. Schematically:

<defaults>
/ screencolor = (255, 255, 255)
/ fontstyle = ("Arial", 20pt)
</defaults>

<block example>
/ trials = [1-16 = noreplace(near_present, near_absent, far_present, far_absent)]
</block>

<values>
/ itemnumber = 1
</values>

<list itemnumbers>
/ poolsize = 16
</list>

<trial near_present>
/ ontrialbegin = [
    values.itemnumber = list.itemnumbers.nextindex;
]
/ stimulustimes = [0=fixation; 500=TargetWordNear; 1000=TargetImagePresent]
/ timeout = 20000
/ correctresponse = ("s")
/ validresponse = ("s", "a")
</trial>

<trial near_absent>
/ ontrialbegin = [
    values.itemnumber = list.itemnumbers.nextindex;
]
/ stimulustimes = [0=fixation; 500=TargetWordNear; 1000=TargetImageAbsent]
/ timeout = 20000
/ correctresponse = ("s")
/ validresponse = ("s", "a")
</trial>

<trial far_present>
/ ontrialbegin = [
    values.itemnumber = list.itemnumbers.nextindex;
]
/ stimulustimes = [0=fixation; 500=TargetWordFar; 1000=TargetImagePresent]
/ timeout = 20000
/ correctresponse = ("s")
/ validresponse = ("s", "a")
</trial>

<trial far_absent>
/ ontrialbegin = [
    values.itemnumber = list.itemnumbers.nextindex;
]
/ stimulustimes = [0=fixation; 500=TargetWordFar; 1000=TargetImageAbsent]
/ timeout = 20000
/ correctresponse = ("s")
/ validresponse = ("s", "a")
</trial>

<text TargetWordNear>
/ items = TargetWordNear_items
/ select = values.itemnumber
</text>

<item TargetWordNear_items>
/ 1 = "near 01"
/ 2 = "near 02"
/ 3 = "near 03"
/ 4 = "near 04"
/ 5 = "near 05"
/ 6 = "near 06"
/ 7 = "near 07"
/ 8 = "near 08"
/ 9 = "near 09"
/ 10 = "near 10"
/ 11 = "near 11"
/ 12 = "near 12"
/ 13 = "near 13"
/ 14 = "near 14"
/ 15 = "near 15"
/ 16 = "near 16"
</item>

<text TargetWordfar>
/ items = TargetWordfar_items
/ select = values.itemnumber
</text>

<item TargetWordfar_items>
/ 1 = "far 01"
/ 2 = "far 02"
/ 3 = "far 03"
/ 4 = "far 04"
/ 5 = "far 05"
/ 6 = "far 06"
/ 7 = "far 07"
/ 8 = "far 08"
/ 9 = "far 09"
/ 10 = "far 10"
/ 11 = "far 11"
/ 12 = "far 12"
/ 13 = "far 13"
/ 14 = "far 14"
/ 15 = "far 15"
/ 16 = "far 16"
</item>

<text TargetImagepresent>
/ items = TargetImagepresent_items
/ select = values.itemnumber
</text>

<item TargetImagepresent_items>
/ 1 = "present 01"
/ 2 = "present 02"
/ 3 = "present 03"
/ 4 = "present 04"
/ 5 = "present 05"
/ 6 = "present 06"
/ 7 = "present 07"
/ 8 = "present 08"
/ 9 = "present 09"
/ 10 = "present 10"
/ 11 = "present 11"
/ 12 = "present 12"
/ 13 = "present 13"
/ 14 = "present 14"
/ 15 = "present 15"
/ 16 = "present 16"
</item>

<text TargetImageabsent>
/ items = TargetImageabsent_items
/ select = values.itemnumber
</text>

<item TargetImageabsent_items>
/ 1 = "absent 01"
/ 2 = "absent 02"
/ 3 = "absent 03"
/ 4 = "absent 04"
/ 5 = "absent 05"
/ 6 = "absent 06"
/ 7 = "absent 07"
/ 8 = "absent 08"
/ 9 = "absent 09"
/ 10 = "absent 10"
/ 11 = "absent 11"
/ 12 = "absent 12"
/ 13 = "absent 13"
/ 14 = "absent 14"
/ 15 = "absent 15"
/ 16 = "absent 16"
</item>

<text fixation>
/ items = ("+")
/ color = (0, 0, 0)
/ txbgcolor = (255, 255, 255)
/ fontstyle = ("Arial", 30pt)
/ erase = false
</text>
Dave
Dave
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Karolina K. - 5/10/2020
I exceeded the upload size in my first attempt and now I can not attach reduced and zipped image folder.

I don't understand what you want to do here.
Karolina K.
Karolina K.
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I exceeded the upload size in my first attempt and now I can not attach reduced and zipped image folder.
Karolina K.
Karolina K.
New Member (41 reputation)New Member (41 reputation)New Member (41 reputation)New Member (41 reputation)New Member (41 reputation)New Member (41 reputation)New Member (41 reputation)New Member (41 reputation)New Member (41 reputation)
Group: Forum Members
Posts: 3, Visits: 16
Hi,
I am working on a visual search task where I display a target word followed by a search scene. I have 2 variables: one called"TargetWord", and the other "TargetImage". Both have two levels, so that there are two possible text words for each scene referred to as Near and Far, and two possible versions of a scene for each target word that I refer to as Present and Absent.  

I managed to create lists that tie those stimulus pairs accurately, but I run into a problem that both the Target Word and Target Image are being repeated within a block. They never repeat in the same combination of conditions meaning that for example I end up having 1_NearPresent and again 1_NearAbsent in a block or 1_NearPresent and then 1_FarPresent. I need each stimulus to be seen under one of the combination of conditions only. I played with different "select" options quite a bit and nothing seems to work. I attached a shortened (cut by half) version of the script, but I still used 18 stimuli because I wanted the repetitions to be apparent.  

Another thing that I didn't get to yet, but thought it might be worth mentioning now, is that I need to counterbalance the conditions. That is I need to be able to control which of the 4 combination of conditions the stimulus was displayed for participant one, so that the next participants can receive the second, third and fourth combination. What method allows to achieve that?   

I would greatly appreciate any help.
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