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Join Date: Oct 2014
jcroot is on a distinguished road Posts: 11
repeat trial once max, Posted September 28th, 2018 #1
Hi, all,
I am building a stop-signal task in which I want to limit stop trials to be presented only once or two in a row maximum but no more.

So - go, stop, stop, go, stop, go

but not - go, stop, stop, stop, go

I tried to solve this by using a stop counter that increments to 1 every time a stop trial is presented, and then this parameter is reset every time a go trial is presented, and under trial rules choosing present only when stop counter is <2.

The problem is that this will not allow the stop trial to be presented at the end of a given block in which the third and second to the last trials are stop, stop.

I think I've worked around this problem by specifying a second rule for stop trials (attached). There are 64 trials total, 16 stop trials and 48 go trials.

For stop trials, present trial only if the following criteria are met:

Parameter "Stop counter" <2 OR
Number of times this trial has been presented <16 AND
Number of trials presented in block = 63

This seems like it should work, but testing is difficult since presentation of two stop trials at the third and second to last trials in a block happens infrequently.

Can anyone weigh in to let me know that this should work or alternative solutions?
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Join Date: Aug 2006
Location: San Pedro, CA
Hisham is on a distinguished road Posts: 1,218
Posted October 2nd, 2018 #2
James, this would be faster addressed over the phone. Please call me at 1-310-548-9595.
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