<div dir="ltr">Thank you for the suggestions. Sorry for the small font, I thought that a long list of code would be neater if it was slightly smaller, but apparently Google's preset font sizes do not show up well in e-mails. <div><br></div><div>The short version is: I need a trial of task 1 to be followed by another trial of task 1 three out of four times, and by a trial of task 2 one out of four times, and vice-versa (first If statement), but the same trial can't come up more than five times in a row (second If statement). The current version of the script should do that, but doesn't, and I don't know why.<br><div><br></div><div>Creating nested lists for both tasks is definitely a good idea, that would reduce the number of SetWeight commands needed by 75%, but as for restructuring the lists: I have thought about using multiple lists but I don't see a way of dynamically varying trial probabilities while preserving randomness and ensuring that each stimulus is used exactly twice. I will take another look at it, though.</div><div><br></div><div>I did not know about List.Reset but if it does what I assume it does, I cannot use it because the weight adjustments are needed for the next trial. My trial procedure looks roughly like:</div><div><br></div><div>Facelist</div></div><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;"><div><div>StimulusSlide</div></div></blockquote><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;"><div>ResponseSlide</div></blockquote><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;"><div>SetWeightScript</div></blockquote><div><br></div><div>Which task to select in the next trial depends on what task the current trial is. Unless I misunderstand, adding List.Reset would undo all the changes made by the script and choose the next trial with equal probability for both tasks.</div><div><br></div><div>Does this procedure design cause problems? Since I do not know how to refer to an attribute of the previous trial, this seemed like the only possible way of doing what I'm trying to do.</div><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;"><div> </div></blockquote><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;"><div> </div></blockquote><div><div><br>On Monday, March 31, 2014 9:24:10 PM UTC+2, McFarlane, David wrote:<blockquote class="gmail_quote" style="margin: 0;margin-left: 0.8ex;border-left: 1px #ccc solid;padding-left: 1ex;">Just a few comments offhand...
<br>
<br>First, the text for your code excerpt appears in little tiny type in
<br>my e-mail reader, I had to copy & paste it into a text editor just to
<br>read it. Please spare me that trouble in the future.
<br>
<br>Second, whenever I see someone mucking about that much with List
<br>weights in code, I wonder whether the same end might be better
<br>accomplish by some restructuring with multiple Lists or nested
<br>Lists. We all find it difficult to rethink and restructure a program
<br>once we feel it is close to working, but many times I have found that
<br>that sort of rethinking and restructuring has not only fixed the
<br>immediate problem, but also solved other imminent problems. You may
<br>indeed have a good reason for managing List weights in this case, but
<br>think about it.
<br>
<br>Third, I confess I found too much detail in the description for me to
<br>work through it all. So I will just toss out the most common mistake
<br>that people make when modifying Lists in code -- did you remember to
<br>use List.Reset (in your case, FaceList.Reset) after making all these
<br>changes? Your code excerpt does not include that line.
<br>
<br>Regards,
<br>-----
<br>David McFarlane
<br>E-Prime training
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<br>
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<br>
<br>At 3/31/2014 07:59 AM Monday, LaurensK90 wrote:
<br>>I'm trying to create a task-switching experiment that requires
<br>>participants to categorize a face by either emotion or gender, as
<br>>indicated by a pre-stimulus cue. Repeat trials (emotion trial
<br>>following an emotion trial, or gender trial following a gender
<br>>trial) need to be more common than switch trials (emotion trial
<br>>following a gender trial, etc.), with a 1:3 switch:repeat ratio. To
<br>>achieve this, I wrote this script:
<br>>
<br>>Dim e as integer
<br>>Dim g as integer
<br>>'Weighting trials to make repeats more likely than switches
<br>>If c.GetAttrib("TaskNr") = "0" Then
<br>> FaceList.SetWeight 1, "3"
<br>> FaceList.SetWeight 2, "1"
<br>> FaceList.SetWeight 3, "3"
<br>> FaceList.SetWeight 4, "1"
<br>> FaceList.SetWeight 5, "3"
<br>> FaceList.SetWeight 6, "1"
<br>> FaceList.SetWeight 7, "3"
<br>> FaceList.SetWeight 8, "1"
<br>> 'Counter to keep track of how many consecutive emotion trials have occured
<br>> e = e+1
<br>> g = 0
<br>>
<br>>ElseIf c.GetAttrib("TaskNr") = "1" Then
<br>> FaceList.SetWeight 1, "1"
<br>> FaceList.SetWeight 2, "3"
<br>> FaceList.SetWeight 3, "1"
<br>> FaceList.SetWeight 4, "3"
<br>> FaceList.SetWeight 5, "1"
<br>> FaceList.SetWeight 6, "3"
<br>> FaceList.SetWeight 7, "1"
<br>> FaceList.SetWeight 8, "3"
<br>> 'Counter to keep track of how many consecutive gender trials have occured
<br>> g = g+1
<br>> e = 0
<br>>
<br>>End If
<br>>'Set weights for emotion or gender trials to zero to prevent too many repeats
<br>>'If e >= 5 Then
<br>>' FaceList.SetWeight 1, "0"
<br>>' FaceList.SetWeight 2, "1"
<br>>' FaceList.SetWeight 3, "0"
<br>>' FaceList.SetWeight 4, "1"
<br>>' FaceList.SetWeight 5, "0"
<br>>' FaceList.SetWeight 6, "1"
<br>>' FaceList.SetWeight 7, "0"
<br>>' FaceList.SetWeight 8, "1"
<br>>' e = 0
<br>>
<br>>'ElseIf g >= 5 Then
<br>>' FaceList.SetWeight 1, "1"
<br>>' FaceList.SetWeight 2, "0"
<br>>' FaceList.SetWeight 3, "1"
<br>>' FaceList.SetWeight 4, "0"
<br>>' FaceList.SetWeight 5, "1"
<br>>' FaceList.SetWeight 6, "0"
<br>>' FaceList.SetWeight 7, "1"
<br>>' FaceList.SetWeight 8, "0"
<br>>' g = 0
<br>>
<br>>'End If
<br>>
<br>>The first If statement looks at the current trial type and increases
<br>>the weights of every same trial type to 3, and every other trial
<br>>type to 1. The trial types are in alternating rows in FaceList. The
<br>>script is at the end of the core experimental procedure, meaning
<br>>that the weights are adjusted after each trial is complete. If I've
<br>>done this correctly, there should be three times as many repeat
<br>>trials as switch trials, but this doesn't seem to happen. I ran the
<br>>experiment with 768 trials, then copied the TaskNr column (filled
<br>>with 0s and 1s) out of the data file and pasted it in Excel. Then I
<br>>added every cell to the cell below it to determine whether the trial
<br>>was a repeat (0 or 2) or a switch (1), and counted those. This
<br>>always results in roughly equal numbers of 0s, 1s and 2s (a 1:2
<br>>switch ratio) while running the task without the script gives you as
<br>>many 1s as 0s and 2s combined (a 1:1 switch ratio). So the switch
<br>>ratio works as expected without the script but not with it. I'm
<br>>wondering if there's something wrong with the way I'm counting these
<br>>because changing the weights from 3 to 4 or 5 makes the maximum
<br>>number of consecutive repeats increase. With weights set to 3, 10
<br>>gender tasks in a row occur 20 times, and when set to 5, 10 in a row
<br>>occur 46 times. So it's strange the actual switch ratio isn't affected.
<br>>
<br>>The second if statement tries to ensure that there are no more than
<br>>5 consecutive trials of the same type, by looking at a counter that
<br>>increments every time a trial passes of one type, and resets every
<br>>time a trial passes of the other type. If the counter reaches 5, it
<br>>sets all the trials of the same type to zero so it can't select them
<br>>again. I haven't tested this extensively but the first time I ran
<br>>the experiment with it, the number of consecutive repeats was even
<br>>higher than normal! Have I made a mistake in this script, or might
<br>>this be the same problem as the previous one?
<br>>
<br>>I've asked official E-Prime support for help as well, a week ago,
<br>>but haven't heard back from them yet, so any additional assistance
<br>>would be appreciated.
<br>
<br>
<br></blockquote></div></div></div>
<p></p>
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