setting two different conditions for the experiment as a part of the initial script

[Kelsey A Brown]

Hello Everyone, 

I am trying to use E-prime to build a stop signal frustration task, but I have encountered a few complications in building the task. 

At the moment, I am trying to create an initial script that would allow E-prime to automatically run a participant in a condition (high frustration or low frustration) depending on the participant number that I input before running the experiment. 

So for example, if I wanted to run 80 participants, half would be placed in the high frustration condition and the other half would be placed in the low frustration condition. 

I have some ideas about how this could theoretically be carried out, but I'm not sure if/how this can actually be implemented in the script. For example, I would want the initial script to begin by telling the program to pull 40 random numbers 1-80 (I would need to somehow make the same 40 numbers be pulled each time). The 40 numbers pulled would be placed in the low frustration condition where pctcorrect (percent correct)=.80. 

If else, (so if one of the other 40 numbers were pulled), place the participant in a high frustration condition where  pctcorrect (percent correct)=.30. 

e.g. If I were running the program and I typed in my participant number as 3 and 3 was one of the random numbers pulled between 1 and 80 then the program would automatically run the stop signal task placing the participant in the low frustration condition where pctcorrect=.80 (where participants could accurately inhibit on 80% of stop signal trials). 

However, if the participant ID number was 8 and 8 was not one of the 40 random numbers initially pulled between 1 and 80 then the program would place the participant in the high frustration condition where pctcorrect=.30. 

Is this something that is possible in E-prime? 

I hope this makes sense. Thanks in advance for your input! 

-Kelsey 

[Vinson, David]

Dear Kelsey,

There's a really easy way to set this up using E-Prime: using Offset by Subject selection to determine at the start of a run which condition a Subject is in, selecting it from a higher level List.

Create a List with two rows, one with procedure HighFrustProc and the other LowFrustProc, weight = 1. This List can have the attribute pctcorrect (.80 for low frustration, .30 for high frustration). Then set Selection properties of this List to Order: Offset, Order by: Subject. And Reset/Exit to Exit List: After 1 Sample.

This way odd numbered subjects would run the HighFrust (or whatever is in the first line of the List) and even numbered, the LowFrust.

Then each of these two Procedures would contain the other various elements of your experiment (e.g. the item Lists and trial Procedures), using the same objects and sub-procedures wherever possible to ensure that the two conditions are otherwise the same.

If you don't like the strict alternation of odd/even Subject numbers, could take the same kind of approach by creating a random sequence in advance and using this to populate this List object (ie, 80 rows, again offset by subject number). Not elegant but very easy and transparent to implement.

best,
DavidV


________________________________________
From: e-p...@googlegroups.com [e-p...@googlegroups.com] on behalf of Kelsey A Brown [kbr...@wellesley.edu]
Sent: 08 September 2014 22:27
To: e-p...@googlegroups.com
Subject: setting two different conditions for the experiment as a part of the initial script

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[David McFarlane]

Kelsey,

What David V said, except that I would use Counterbalance by Subject
selection instead of Offset by Subject. Counterbalance does pretty
much the same as Offset plus Reset/Exit After 1 Sample, but may be a
bit more convenient. Please see discussions at
https://groups.google.com/d/topic/e-prime/JtLh6DxqCbs and
https://groups.google.com/d/topic/e-prime/CHntiIUbUmc .


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David McFarlane
E-Prime training
online: http://psychology.msu.edu/Workshops_Courses/eprime.aspx
Twitter: @EPrimeMaster (https://twitter.com/EPrimeMaster)

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[Kelsey A Brown]

Dear David V, 

Thank you for the incredibly detailed and easy to understand instructions. I figured it was something that could be accomplished in E-prime, but I was unsure of the exact steps to follow to make it happen. I appreciate the invaluable assistance!

Best, 

Kelsey  

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[Kelsey A Brown]

Dear David McFarlane, 

I also want to thank you for taking the time to answer my question and for providing links to similar discussions. I like the idea of using the counterbalance by subject option. I will certainly implement both your suggestion and David V's instructions when I return to building my task tomorrow. 

Thank you, 

Kelsey 

[Kelsey A Brown]

Hello Everyone, 

I just have a follow up question to my question above. I was able to create the list for the two groups with pctcorrect as an attribute following all of the steps David V and David McFarlane provided; however, I have a brief question about running the experiment with this setup. Will I be able to determine which trialproc a subject was placed in (highfrustrationproc or lowfrustrationproc) or is this something I would have to designate beforehand? I figure with the counterbalancing I wouldn't have to designate this, but I would need to know which procedure each participant completed. Also, in the experiment object properties startup information, I have group checked where I can input either 1 or 2 to state which condition the participant is assigned.Is this beginning group step necessary if I have E-prime counterbalance subjects into the two conditions using the list I created? I guess the main question I am asking is if I can simple uncheck group in the experiment object properties start-up information given that I have counterbalanced the list of procedures?  

Thanks, 

Kelsey 

[David Vinson]

Hi Kelsey,

You should be able to tell which trialproc a subject was in: if you designate this in a top-level List it will appear as Procedure[Block] in the .edat2 file.

As you describe it, Group is redundant, possibly subject to user error (if you mis-key Group it has no effect on the condition run) and less informative than Procedure[Block] which has a descriptive name rather than just values of 1/2. 

An alternative is to keep Group in your startup and use it rather than Subject for counterbalancing.

best,
DavidV

On 12/09/2014 20:45, Kelsey A Brown wrote:

Hello Everyone, 

I just have a follow up question to my question above. I was able to create the list for the two groups with pctcorrect as an attribute following all of the steps David V and David McFarlane provided; however, I have a brief question about running the experiment with this setup. Will I be able to determine which trialproc a subject was placed in (highfrustrationproc or lowfrustrationproc) or is this something I would have to designate beforehand? I figure with the counterbalancing I wouldn't have to designate this, but I would need to know which procedure each participant completed. Also, in the experiment object properties startup information, I have group checked where I can input either 1 or 2 to state which condition the participant is assigned.Is this beginning group step necessary if I have E-prime counterbalance subjects into the two conditions using the list I created? I guess the main question I am asking is if I can simple uncheck group in the experiment object properties start-up information given that I have counterbalanced the list of procedures?  

Thanks, 

Kelsey 

On Monday, September 8, 2014 5:27:08 PM UTC-4, Kelsey A Brown wrote:

Hello Everyone, 

I am trying to use E-prime to build a stop signal frustration task, but I have encountered a few complications in building the task. 

At the moment, I am trying to create an initial script that would allow E-prime to automatically run a participant in a condition (high frustration or low frustration) depending on the participant number that I input before running the experiment. 

So for example, if I wanted to run 80 participants, half would be placed in the high frustration condition and the other half would be placed in the low frustration condition. 

I have some ideas about how this could theoretically be carried out, but I'm not sure if/how this can actually be implemented in the script. For example, I would want the initial script to begin by telling the program to pull 40 random numbers 1-80 (I would need to somehow make the same 40 numbers be pulled each time). The 40 numbers pulled would be placed in the low frustration condition where pctcorrect (percent correct)=.80. 

If else, (so if one of the other 40 numbers were pulled), place the participant in a high frustration condition where  pctcorrect (percent correct)=.30. 

e.g. If I were running the program and I typed in my participant number as 3 and 3 was one of the random numbers pulled between 1 and 80 then the program would automatically run the stop signal task placing the participant in the low frustration condition where pctcorrect=.80 (where participants could accurately inhibit on 80% of stop signal trials). 

However, if the participant ID number was 8 and 8 was not one of the 40 random numbers initially pulled between 1 and 80 then the program would place the participant in the high frustration condition where pctcorrect=.30. 

Is this something that is possible in E-prime? 

I hope this makes sense. Thanks in advance for your input! 

-Kelsey 

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David Vinson, Ph.D.
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Experimental Psychology
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