Variable ISI

[David McFarlane]

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the courtesy of posting their reply back here for the sake of others.

That said, here is my take...

Not sure if this answers what you are asking but...

You can "introduce" the specified ISI values by entering them as an 
attribute ("column") in a List, and then using the bracket notation 
to supply an attribute reference in the Duration property of some 
E-Object.  E.g., I imagine that you have something happen between 
your stimuli (e.g., a BlankText).  In your TrialList you could add an 
attribute called ISIDur, and then in the Duration of BlankText put 
"[ISIDur]" (sans the quotes, of course).  You should get the idea from there.

This is easiest if you use a simple TrialList run in Sequential order 
(common practice for fMRI here).  If you need E-Prime to randomize 
things for you on-the-fly, then things could get more complicated 
(depending on your design), and you might have to resort to nested 
Lists (see Appendix C of the User's Guide), or even a bit of inline 
code to randomize the ISI values.  But the principle of using an 
attribute reference remains the same.

Also, if you have not already, then please work through *all* the 
tutorials in *all* the manuals that came with E-Prime (Getting 
Started Guide, User's Guide, Technical Reference Guide) before you 
proceed further.  That will answer all the beginner questions.

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


At 4/19/2012 09:35 AM Thursday, you wrote:
>I have a study with variable ISI between events (stimuli)
>
>E.g
>
>Event A - ISI(Variable)
>Event B - ISI(Variable)
>
>The timing (and order of presentation) between events has been 
>worked our carefully to introduce a jitter (i.e., variable delay) to 
>optimize the experiment for fMRI & I have a text file with the 
>timing information for the onset of my events.
>
>
>For example:
>
>Event           Event Onset TIme (secs)
>----------------------------------------------------
>
>        A         14.4
>        B         18.1
>        A         23.8
>        B         30.6
>
>I am not sure how to introduce this timing information into my 
>Eprime script in a simple way.
>Sorry if the answer is obvious and I just missed it
>
>Thank you for you help in advance!
>
>Liat

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