How to Repeat Random Trial Properties

[Benny Liebold]

Hi there 

Usually I feel confident when dealing with inline scripts, but now I feel lost: In my experiment I basically would like to have a list with 30 trials that is run 3 times (i.e. 3 cycles). Initially, this list is blank and should be filled with random properties (faces and objects) during the first cycle. In the second and third cycle, the list should repeat the order of matched faces and objects that was generated during the first cycle. Thus:

1. Cycle: generate randomly matched faces and objects

2. Cycle: repeat the pregenerated list

3. Cycle: repeat the pregenerated list again

I tried both using jump-commands and edited the list to run three cycles, but I still get the following issue: After the first cycle, the script terminates during the image display. I presume that the list is reset to its initial state after the first cycle, which results in an empty list, from which no image displays can be generated. 

Does anyone have an idea on how to get the second and third cycle to repeat the values from the first cycle?

Cheers

Benny

[David McFarlane]

Benny,

If you just want to re-run the same List in the same randomized order
as before, then you might use the ExplicitOrder facility, see that
topic in the E-Basic Help facility. This requires a bit of inline
code during the first run of the List, and can get a bit
tricky. Make sure to Reset your List after setting it to the ExplicitOrder!

If you have more complex needs for the subsequent runs, you could use
the technique shown in the Study-Recall example downloadable from the
PST website. In this case, you may build a new List during the run
of the first List, and then run the new List for the later
runs. Again, you must Reset the List after making changes and before running!

Finally, if you do not really need E-Prime to generate the "random"
order, then you could generate one random order for your List outside
of E-Prime, and then just let E-Prime run the List each time in
Sequential order. We often do things this way for fMRI experiments,
where doing randomization on the fly might result in spurious
mulitcollinearity that prevents analysis.

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

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