Adjusting length of trial based on performance

[David McFarlane]

Rachel,

Stock reminder:  1) I do not work for PST.  2) PST's trained staff 
takes any and all questions at 
http://support.pstnet.com/e%2Dprime/support/login.asp , and they 
strive to respond to all requests in 24-48 hours (although current 
estimates are more like 10 days) -- this is pretty much their 
substitute for proper documentation, so make full use of it.  3) If 
you do get an answer from PST Web Support, please extend the courtesy 
of posting their reply back here for the sake of others.

That said, here is my take...

For a hint on how to programmatically adjust stimulus durations, 
first study Chapter 4, "Using E-Basic", of the User's Guide that came 
with E-Prime.  Then look at the "ContingentStimulusDuration" example 
downloadable from PST.

For another hint on how to make trials contingent on subject 
performance, see the "CriterionForExit" example downloadable from PST.

-- David McFarlane, Professional Faultfinder


At 8/4/2010 08:53 AM Wednesday, you wrote:

>I am working on a program that does the following:
>
>Participants are presented with a fixation cross for 500ms, followed
>by a fixation cross and 2 words (one to the left of the fixation cross
>and one to the right). Then, a string of "X"es with either a "C" or
>"O" in the middle replaces one of the words. The participant's job is
>to indicate which letter they see by pressing C or O on the response
>box.
>
>If the participant gets 3 trials in a row incorrect and/or does not
>respond before the next trial begins during 3 trials in a row, how can
>I have e-prime adjust the presentation time of the string of "X"es so
>that they are presented longer? And then, once they get 10 trials in a
>row correct, how can I reduce the presentation time of the "X"es? In
>other words, I would like to be able to adjust the presentation time
>of the "X"es throughout the program based upon correct and incorrect/
>no responses. Any thoughts on how to do this would be much
>appreciated.
>
>Thank you,
>Rachel

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