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picture selection

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SimonaH.	SimonaH. posted 9 Years Ago ANSWER Post Details Share Post
Group: Forum Members Posts: 6, Visits: 48	Of course, makes sense. I confused the amount of pictures in a master list, with the amount of which were supposed to be selected per list. Now it seems to work. Thanks!
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Dave	Dave posted 9 Years Ago ANSWER Post Details Share Post
Group: Administrators Posts: 13K, Visits: 104K	The example in my response has only 4 items, hence the <list> only has a poolsize equal to 4. For more items, you need to adjust it as needed. <list masterlist> / poolsize = 16 / selectionrate = always </list> You need to adjust the /onexptbegin logic accordingly as well.
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SimonaH.	SimonaH. posted 9 Years Ago ANSWER Post Details Share Post
Group: Forum Members Posts: 6, Visits: 48	Hi, thanks for the answer. I tried to implement what you suggested (exactly), however there is still one occurring problem: I keep being presented with only the first 4 pictures from the master list over and over again (so the rest of the 16 pics does not get selected). Where could be the problem? Simona
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Dave	Dave posted 9 Years Ago ANSWER Post Details Share Post
Group: Administrators Posts: 13K, Visits: 104K	Your idea is along the correct lines, your syntax is erroneous in various places. (1) Have a master <list> containing the 16 item numbers for your 16 different pictures (2) At the beginning of the experiment populate your 4 empty <lists> representing the 4 conditions with 4 random items from that masterlist each. There is no need to remove anything from the master list. (3) Use the condition lists for item selection in your stimulus elements. In a nutshell: <expt> / onexptbegin = [list.a.appenditem(list.masterlist.nextindex); list.a.appenditem(list.masterlist.nextindex); list.b.appenditem(list.masterlist.nextindex); list.b.appenditem(list.masterlist.nextindex); ] / blocks = [1=ablock; 2=bblock] </expt> <block ablock> / trials = [1-2=atrial] </block> <block bblock> / trials = [1-2=btrial] </block> <trial atrial> / stimulusframes = [1=atxt] / validresponse = (57) </trial> <trial btrial> / stimulusframes = [1=btxt] / validresponse = (57) </trial> <list masterlist> / poolsize = 4 / selectionrate = always </list> <list a> </list> <list b> </list> <text atxt> / items = myitems / select = list.a.nextvalue </text> <text btxt> / items = myitems / select = list.b.nextvalue </text> <item myitems> / 1 = "Item 1" / 2 = "Item 2" / 3 = "Item 3" / 4 = "Item 4" </item>
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SimonaH.	SimonaH. posted 9 Years Ago Topic Details Share Topic
Group: Forum Members Posts: 6, Visits: 48	Hi, I have a question on how to best programm a random selection of pictures from one pool into separate picture pools that starts at the beginning of a trial. I have a pool of 16 pictures and at the beginning of an experiment I want them to be randomly assigned into 4 separate pools: 4 pictures per pool. These picturs will then be drawn at and presented in 4 different within design conditions (reperesnted by trials), where also other characteristics are counterbalanced (e.g. picture position). I tried to accomplish it by creating a central list of 16 pictures and programm a very first trial of the experiment so that it randomly draws 4 pictures into one list and erases them from the central list and the same should happen for the next 3 lists. Then the lists are used as a “selection” reference in picture elements, as lists cannot be really used as “item” elements in trials etc. However, it does not seem to work well, I keep getting these errors: “Error evaluating ´100´/: Unknown error.” “Unable to initialze <picture xy> item number 0. Verify the item exists and its correctly defined.” Any ideas? Thanks! Here is my script: <item all_central> /1=picture1 /2=picture2 /... /16=picture16 </item> <picture all_central> / items = all_center /select = noreplace / position = (50, 50) /size = (550,600) </picture> <list all_central> / items= (all_central) </list> <list congruent_a> / items= (list.all_central) /poolsize= 4 /selectionmode = random </list> <trial remove1> / ontrialbeginning= [list.all_central.removeitem(list.congruent_a);] /timeout = 1 </trial> <list incongruent_a> / items= (list.all_central) /poolsize= 4 /selectionmode = random </list> <trial remove2> / ontrialend= [list.all_central.removeitem(list.incongruent_a);] /timeout = 1 </trial> <list congruent_b> / items= (list.all_central) /poolsize= 4 /selectionmode = random </list> <trial remove3> / ontrialend= [list.all_central.removeitem(list.congruent_b);] /timeout = 1 </trial> <list incongruent_b> / items= (list.all_central) /poolsize= 4 /selectionmode = random </list> <picture xyz_left_congruent_a> /select = list.congruent_a / position = (25, 50) /size = (250,300) </picture> <picture xyz_left_congruent_b> /select = list.congruent_b / position = (25, 50) /size = (250,300) </picture> <picture xyz_right_congruent_a> /select = list.congruent_a / position = (75, 50) /size = (250,300) </picture> <picture xyz_right_congruent_b> /select = list.congruent_b / position = (75, 50) /size = (250,300) </picture> <picture xyz_left_incongruent_a> /select = list.incongruent_a / position = (25, 50) /size = (250,300) </picture> etc.. trial example: <trial l_congruent_left_face_a> /inputdevice=mouse /validresponse = ("liking_button","disliking_button") /stimulustimes = [500=fixation_cross; 1100=face_center; 1100=xyz_left_congruent_a; 2700=facegaze_left; 3500 = x_button, y_button] </trial>
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