One question: I want to have random trials for the serial reaction time task. The trials items must be 1 2 3 4…And the random trials sequence should be for example: 1-3-4-2-3-1-2…
There can be no item repeats…
How can I make such a randomizied sequence without item repeats.
Could someone help me?
Thanks,
Cigdem
and
and the random trials should be equal across subjects.
Turn randomization On in the Block Editor’s Randomize tab.
thanks 
ISI`s
Dear Hisham,
but it is complicated if I want to have interstimulus interval between the items.
Without interval it is very easy: I can define my 4 events. Then I can define for exp. 16 trials, and randomize them. And define 1 block for 16 trials. So at the end I have 64 random trials.
but how is possible, when I want to have ISI between 4 items. Now I can not randomize my trials, since this will also cause ISI`s to be randomized like the 4 items.
Thanks,
Cigdem
You can add an ISI as a fifth event within a trial. When trials are randomized within a block, events within a trial are kept in the same order unless you explicitly turn event randomization on yourself.
I hope that I helped more than I confused! 
Hisham.
not clear
Dear Hisham,
I am not sure if it was clear.But before each event there must be a ISI. I show four different pictures at 4 locations, and every time only one picture…A trial is a foursomesequence (like 1-3-2-4)
…And the sequence should change randomly…
Could you help me pls,
Cigdem
Are you trying to get the events to show at specific intervals, or are you wanting a constant delay after the response and before the next event?
If you want the events at specific intervals, you can set up a time limit in the event’s input tab. If instead, you just want a constant ISI between the events, you can create a single ISI event that is run from each stimulus’ feedback. Done either of these ways, the ISI would not be affected by randomizing the events within the trial.
Dear Hank,
I want to have a constant delay between the events.
thanks for your answer!
Cigdem