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

[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-prime at googlegroups.com [e-prime at googlegroups.com] on behalf of Kelsey A Brown [kbrown6 at wellesley.edu]
Sent: 08 September 2014 22:27
To: e-prime at googlegroups.com
Subject: setting two different conditions for the experiment as a part of the initial script

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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