AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

History of AFNI updates  

Previous Message Next Message
Message List New Topic Print View
|
Gang Chen
June 06, 2006 02:54PM
> Stimuli are presented for ½ a TR (TR=2 sec).

Half of a TR, or 1 or 2 TR's? Your script shows that you are looking for events with a duration of 2 TR's (-nblock i 2.0).

> Using markov chain ignores the –nreps (20) and I get an unequal
> occurrence of my three stimuli

I don't see any reason you have to use Markov chain design. Markov chain process is useful if you have some specific restriction among the three events, for example, A is not allowed to follow B.

> using random permuatatioln is not following my restrictions
> (range of ISI)

Again you don't have to shuffle the output files. However, unfortunately RSFgen seems unable to set an upper limit for ISI although you can implicitly control the average ISI by considering totally number of TR's, repetitions, etc.

Maybe you can try running RSFgen several times with different seeds and sift out those with big ISI's?

Gang
Reply Quote
RSS
Subject Author Posted

Finding optimal stimulus seq.

Sharon R.S June 06, 2006 10:05AM

Re: Finding optimal stimulus seq.

Gang Chen June 06, 2006 02:54PM