jitter in rapid event related design

[lislog]

Dear colleagues
I want to program an e-prime paradigm for fMRI with varying stimulus
onset time, in order to jitter the BOLD responses. I guess this has to
be done with a InLine-object in the TrialProc- object. What are the
comands that have to be written into the InLine-object? Or do you have
other suggestions how to introduce into the TrialList-object a
variablel stimulus onset time?
best lislog

[ben robinson]

you could certainly do this with an inline script, or you could do it just using the built-in objects.
here's one way to do it:
say you're using a TextDisplay item to display your stimulus, and it's the onset of the TextDisplay item which you would like to jitter.  let's call that TextDisplay2, and immediately before it in the procedure time-line is TextDiplay1 (a blank screen or fixation cross).  go to the duration/input tab in your TextDisplay1, and in the Duration field (also in the PreRelease field) type [jitter].  now TextDisplay1 is trying to determine its duration from a column by the name of "jitter" in some higher up List.  so now we need to make that list, and that column within it.
let's say your trial procedure is being called from/run from "List1".  go to List1, and on the same row as you have your procedure being called, create a nested list, called "JitterList", or something.  inside JitterList you need to add a column titled, "jitter", to supply a value for the duration field on your TextDisplay1.  in this column put all the various durations you'd like.  now set JitterList to select items at random.
hope that works.

ben