Hi,
> For event related design, the stimuli interval between interesting stimuli
> should be a exponential distribution. How can I get this " exponential
> distribution"?
There are two simple ways. The first is just to generate an
exponential distribution of inter-stimulus intervals, and put your
events at these intervals.
The simpler and more popular way is to split your experiment into time
bins of - say - 2 seconds, and, for each time bin, decide randomly if
this time bin will contain a event-of-interest or an
event-of-no-interest. This generates a discrete exponential
distribution of ISIs between events-of-interest,
See in particular:
Friston KJ, Zarahn E, Josephs O, Henson RN, Dale AM. Stochastic
designs in event-related fMRI. Neuroimage. 1999 Nov;10(5):607-19.
Best,
Matthew
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