RE: Selection and randomization of pictures within a trial

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RE: Selection and randomization of pictures within a trial

Selection and randomization of pictures within a trial

Author	Message
gracethenoob	gracethenoob posted 8 Years Ago HOT Topic Details Share Topic
Group: Forum Members Posts: 11, Visits: 85	I am having trouble selecting at random and presenting at random within trials. For each trial, there is a target image presented at a specific point within a stream of filler images. Example: 1 = filler23 2 = filler17 3 = filler2 4 = target1 5 = filler6 6 = filler19 7 = filler5 8 = filler4 9 = filler20 10 = filler15 11 = filler8 The constraints are: (1) The 10 filler images are randomly drawn from a pool of 24 images, cannot repeat within a trial, must be presented in a random order, and must be selected anew each trial. (2) There are 5 target images and a different one (using random selection) must be presented every trial. I think the second constraint is straightforward because it works like a regular trial but I cannot figure out how to tackle the first constraint. I have looked at other code in the Inquisit library such as the Simple Attentional Blink code and it seems to have a solution when using single letters but I cannot seem to translate that strategy to pictures. Any tips?
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Dave	Dave posted 8 Years Ago ANSWER Post Details Share Post
Group: Administrators Posts: 13K, Visits: 104K	What works for <text> elements works for <picture> elements as well. Set up ten filler <picture> elements -- <picture filler01> to <picture filler10> -- and have them select from the same item pool via a <list>; reset that list at the start of each <trial>. Set up a single <picture target> element. <trial mytrial> / ontrialbegin = [list.filleritems.reset(); ] / stimulustimes = [0=filler01; 500=filler02; 1000=target; 1500=filler04; 2000=filler05; ...] ... </trial> <picture target> / items = ("t1.jpg", "t2.jpg", "t3.jpg", "t4.jpg", "t5.jpg") </picture> <list filleritems> / poolsize = 24 / selectionrate = always </list> <picture filler01> / items = fillerimages / select = list.filleritems.nextindex </picture> <picture filler02> / items = fillerimages / select = list.filleritems.nextindex </picture> <picture filler03> / items = fillerimages / select = list.filleritems.nextindex </picture> <picture filler04> / items = fillerimages / select = list.filleritems.nextindex </picture> <picture filler05> / items = fillerimages / select = list.filleritems.nextindex </picture> ... <item fillerimages> / 1 = "f1.jpg" / 2 = "f2.jpg" / 3 = "f3.jpg" ... / 24 = "f24.jpg" </item>
	Reply Like 71
gracethenoob	gracethenoob posted 8 Years Ago ANSWER Post Details Share Post
Group: Forum Members Posts: 11, Visits: 85	Thank you for this assistance! It was very helpful :-)
	Reply Like 66
chenxyu	chenxyu posted 2 Years Ago ANSWER Post Details Share Post
Group: Forum Members Posts: 18, Visits: 252	Hi Dave, if I have a total of 1000 pictures and want to randomly select 5 from that pool and present them simultaneously for any given trial, does that mean I have to create a <picture> element for each of the 1000 pictures? Thanks for your help!
	Reply Like 4
Dave	Dave posted 2 Years Ago ANSWER Post Details Share Post
Group: Administrators Posts: 13K, Visits: 104K	+x chenxyu - 11/9/2022 Hi Dave, if I have a total of 1000 pictures and want to randomly select 5 from that pool and present them simultaneously for any given trial, does that mean I have to create a <picture> element for each of the 1000 pictures? Thanks for your help! No, you need five <picture> elements, since you want to display five images simultaneously.
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chenxyu	chenxyu posted 2 Years Ago ANSWER Post Details Share Post
Group: Forum Members Posts: 18, Visits: 252	Thank you! A couple of follow-up questions if you don't mind: I attempted to randomly select 5 pictures from a pool of 1000 pictures and another 4 from another pool of 800 pictures with no replacement (so picture will only present once throughout the experiment). This would mean I will need 9 <picture> elements, right? To do so, I created two lists (List A with 1000 items and List B with 800 items) and within each list, I set /replace = false and /poolsize = 1000 and 800, respectively. Then within those picture elements, I set /selectionrate = experiment. Would this do I what want it to do? I've attached part of the code below if it makes it easier to read. I also want to randomize the position of these pictures. Can you point me to some resources if this question has been answered elsewhere? Finally, if I want to repeat this until all stimuli have been exhausted (i.e., a total of 200 trials, each trial has 5 pictures from list A and 4 from list B), what would you recommend? <item person1-1000> /1= "person1" ... /1000="person1000" </item> <item name1-800> /1="name1" ... /800="name800" </item> <list person> /items=(1,2,....,1000) /replace=false /poolsize=1000 </list> <list name> /items=(1,2,...,800) /replace=false /poolsize=800 <list> <picture person1> /items=person /select=list.person.nextindex /selectionrate=experiment </picture> <picture person2> /items=person /select=list.person.nextindex /selectionrate=experiment </picture> <picture person3> /items=person /select=list.person.nextindex /selectionrate=experiment </picture> <picture person4> /items=person /select=list.person.nextindex /selectionrate=experiment </picture> <picture person5> /items=person /select=list.person.nextindex /selectionrate=experiment </picture> <picture name1> /items=name /select=list.name.nextindex /selectionrate=experiment </picture> <picture name2> /items=name /select=list.name.nextindex /selectionrate=experiment </picture> <picture name3> /items=name /select=list.name.nextindex /selectionrate=experiment </picture> <picture name4> /items=name /select=list.name.nextindex /selectionrate=experiment </picture>
	Reply Like 5
Dave	Dave posted 2 Years Ago ANSWER Post Details Share Post
Group: Administrators Posts: 13K, Visits: 104K	+x chenxyu - 11/9/2022 Thank you! A couple of follow-up questions if you don't mind: I attempted to randomly select 5 pictures from a pool of 1000 pictures and another 4 from another pool of 800 pictures with no replacement (so picture will only present once throughout the experiment). This would mean I will need 9 <picture> elements, right? To do so, I created two lists (List A with 1000 items and List B with 800 items) and within each list, I set /replace = false and /poolsize = 1000 and 800, respectively. Then within those picture elements, I set /selectionrate = experiment. Would this do I what want it to do? I've attached part of the code below if it makes it easier to read. I also want to randomize the position of these pictures. Can you point me to some resources if this question has been answered elsewhere? Finally, if I want to repeat this until all stimuli have been exhausted (i.e., a total of 200 trials, each trial has 5 pictures from list A and 4 from list B), what would you recommend? <item person1-1000> /1= "person1" ... /1000="person1000" </item> <item name1-800> /1="name1" ... /800="name800" </item> <list person> /items=(1,2,....,1000) /replace=false /poolsize=1000 </list> <list name> /items=(1,2,...,800) /replace=false /poolsize=800 <list> <picture person1> /items=person /select=list.person.nextindex /selectionrate=experiment </picture> <picture person2> /items=person /select=list.person.nextindex /selectionrate=experiment </picture> <picture person3> /items=person /select=list.person.nextindex /selectionrate=experiment </picture> <picture person4> /items=person /select=list.person.nextindex /selectionrate=experiment </picture> <picture person5> /items=person /select=list.person.nextindex /selectionrate=experiment </picture> <picture name1> /items=name /select=list.name.nextindex /selectionrate=experiment </picture> <picture name2> /items=name /select=list.name.nextindex /selectionrate=experiment </picture> <picture name3> /items=name /select=list.name.nextindex /selectionrate=experiment </picture> <picture name4> /items=name /select=list.name.nextindex /selectionrate=experiment </picture> <values> / p1_itemnumber = 1 / p2_itemnumber = 1 / p3_itemnumber = 1 / p4_itemnumber = 1 / p5_itemnumber = 1 / n1_itemnumber = 1 / n2_itemnumber = 1 / n3_itemnumber = 1 / n4_itemnumber = 1 </values> <block exampleblock> / trials = [1-200 = exampletrial] </block> <list personitemnumbers> / poolsize = 1000 / selectionrate = always </list> <list nameitemnumbers> / poolsize = 800 / selectionrate = always </list> <trial exampletrial> / ontrialbegin = [ values.p1_itemnumber = list.personitemnumbers.nextindex; values.p2_itemnumber = list.personitemnumbers.nextindex; values.p3_itemnumber = list.personitemnumbers.nextindex; values.p4_itemnumber = list.personitemnumbers.nextindex; values.p5_itemnumber = list.personitemnumbers.nextindex; values.n1_itemnumber = list.nameitemnumbers.nextindex; values.n2_itemnumber = list.nameitemnumbers.nextindex; values.n3_itemnumber = list.nameitemnumbers.nextindex; values.n4_itemnumber = list.nameitemnumbers.nextindex; ] / stimulusframes = [1=person1, person2, person3, person4, person5, name1, name2, name3, name4] / validresponse = (57) </trial> <picture person1> / items = personitems / select = values.p1_itemnumber ... </picture> <picture person2> / items = personitems / select = values.p2_itemnumber ... </picture> <picture person3> / items = personitems / select = values.p3_itemnumber ... </picture> <picture person4> / items = personitems / select = values.p4_itemnumber ... </picture> <picture person5> / items = personitems / select = values.p5_itemnumber ... </picture> <picture name1> / items = nameitems / select = values.n1_itemnumber ... </picture> <picture name2> / items = nameitems / select = values.n2_itemnumber ... </picture> <picture name3> / items = nameitems / select = values.n3_itemnumber ... </picture> <picture name4> / items = nameitems / select = values.n4_itemnumber ... </picture> <item personitems> / 1 = "person_0001.jpg" / 2 = "person_0002.jpg" / 3 = "person_0003.jpg" ... / 998 = "person_0998.jpg" / 999 = "person_0999.jpg" / 1000 = "person_1000.jpg" </item> <item nameitems> / 1 = "name_0001.jpg" / 2 = "name_0002.jpg" / 3 = "name_0003.jpg" ... / 798 = "name_0798.jpg" / 799 = "name_0799.jpg" / 800 = "name_0800.jpg" </item> is the way to set this up properly. /selectionrate = experiment makes no sense, you want new selections every trial, not a single selection in all of the experiment. And the lists need to be set to /selectionrate = always, because you need to sample multiple itemnumbers from each list in each trial (5 and 4 per trial, respectively). Edited 2 Years Ago by Dave
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chenxyu	chenxyu posted 2 Years Ago ANSWER Post Details Share Post
Group: Forum Members Posts: 18, Visits: 252	Thank you! I think I figured it out!
	Reply Like 3