Problem with per-trial weight adjustment using setweight

[LaurensK90]

Hello,
 
I'm trying to create a task-switching experiment that requires participants 
to categorize a face by either emotion or gender, as indicated by a 
pre-stimulus cue. Repeat trials (emotion trial following an emotion trial, 
or gender trial following a gender trial) need to be more common than 
switch trials (emotion trial following a gender trial, etc.), with a 1:3 
switch:repeat ratio. To achieve this, I wrote this script:
 
Dim e as integer
Dim g as integer
'Weighting trials to make repeats more likely than switches 
If c.GetAttrib("TaskNr") = "0" Then

 FaceList.SetWeight 1, "3"
 FaceList.SetWeight 2, "1"
 FaceList.SetWeight 3, "3"
 FaceList.SetWeight 4, "1"
 FaceList.SetWeight 5, "3"
 FaceList.SetWeight 6, "1"
 FaceList.SetWeight 7, "3"
 FaceList.SetWeight 8, "1"
 'Counter to keep track of how many consecutive emotion trials have occured
 e = e+1
 g = 0

ElseIf c.GetAttrib("TaskNr") = "1" Then

 FaceList.SetWeight 1, "1"
 FaceList.SetWeight 2, "3"
 FaceList.SetWeight 3, "1"
 FaceList.SetWeight 4, "3"
 FaceList.SetWeight 5, "1"
 FaceList.SetWeight 6, "3"
 FaceList.SetWeight 7, "1"
 FaceList.SetWeight 8, "3"
 'Counter to keep track of how many consecutive gender trials have occured
 g = g+1
 e = 0

End If
'Set weights for emotion or gender trials to zero to prevent too many 
repeats
'If e >= 5 Then

' FaceList.SetWeight 1, "0"
' FaceList.SetWeight 2, "1"
' FaceList.SetWeight 3, "0"
' FaceList.SetWeight 4, "1"
' FaceList.SetWeight 5, "0"
' FaceList.SetWeight 6, "1"
' FaceList.SetWeight 7, "0"
' FaceList.SetWeight 8, "1"
' e = 0

'ElseIf g >= 5 Then

' FaceList.SetWeight 1, "1"
' FaceList.SetWeight 2, "0"
' FaceList.SetWeight 3, "1"
' FaceList.SetWeight 4, "0"
' FaceList.SetWeight 5, "1"
' FaceList.SetWeight 6, "0"
' FaceList.SetWeight 7, "1"
' FaceList.SetWeight 8, "0"
' g = 0

'End If
 
The first If statement looks at the current trial type and increases the 
weights of every same trial type to 3, and every other trial type to 1. The 
trial types are in alternating rows in FaceList. The script is at the end 
of the core experimental procedure, meaning that the weights are adjusted 
after each trial is complete. If I've done this correctly, there should be 
three times as many repeat trials as switch trials, but this doesn't seem 
to happen. I ran the experiment with 768 trials, then copied the TaskNr 
column (filled with 0s and 1s) out of the data file and pasted it in Excel. 
Then I added every cell to the cell below it to determine whether the trial 
was a repeat (0 or 2) or a switch (1), and counted those. This always 
results in roughly equal numbers of 0s, 1s and 2s (a 1:2 switch 
ratio) while running the task without the script gives you as many 1s as 0s 
and 2s combined (a 1:1 switch ratio). So the switch ratio works as expected 
without the script but not with it. I'm wondering if there's something 
wrong with the way I'm counting these because changing the weights from 3 
to 4 or 5 makes the maximum number of consecutive repeats increase. With 
weights set to 3, 10 gender tasks in a row occur 20 times, and when set to 
5, 10 in a row occur 46 times. So it's strange the actual switch ratio 
isn't affected.
 
The second if statement tries to ensure that there are no more than 5 
consecutive trials of the same type, by looking at a counter that 
increments every time a trial passes of one type, and resets every time a 
trial passes of the other type. If the counter reaches 5, it sets all the 
trials of the same type to zero so it can't select them again. I haven't 
tested this extensively but the first time I ran the experiment with it, 
the number of consecutive repeats was even higher than normal! Have I made 
a mistake in this script, or might this be the same problem as the previous 
one?
 
I've asked official E-Prime support for help as well, a week ago, but 
haven't heard back from them yet, so any additional assistance would be 
appreciated.

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