[open] Open Sesame with fMRI

slincoln

Does anyone use this program for stimulus presentation in fMRI? The program is working beautifully for me, EXCEPT that the trigger the scanner is sending to the program (an = sign), is not triggering the program to start at the right time.
I have it set up

text display

set foreground "white"

set font_size "60"

set description "Presents a display consisting of text"

set maxchar "50"

set align "center"

set content "Get Ready!"

set background "black"

set duration "keypress"

set font_family "mono"

and then for keyboard_response

set correct_response "="

set allowed_responses "="

set description "Collects keyboard responses"

set timeout "infinite"

set flush "yes"

The program starts, but with about a 4 second delay. Any thoughts as to why?

slincoln

Me again.
Is it possible that there's a delay when moving into a loop? All of my text displays BEFORE the loop starts with the exception of the one right before the loop, move immediately with the first key press. Thoughts are most welcome.

sebastiaan

Just for my understanding: The scanner essentially emulates a regular keyboard and sends and = sign to indicate the start of the experiment? And your experiment begins with a keyboard response that waits until an= is pressed? Is that correct?

That should be very straight-forward, and there is no need for a 4s delay. My best guess is that there is some item that holds up the experiment for 4s after the = has been received. Is there perhaps a response item with a 4000ms timeout?

And does the same problem occur when you try a dry-run of experiment with a regular keyboard? I.e. when you actually press the = key yourself?

Another thing might be that for some reason the intertrial interval is extremely long. In this case the 4s delay would not only occur at begin, but after every trial. Is that the case?

If you cannot figure it out, perhaps you could upload your experiment script, or post a screenshot of the overview area + details of the experiment. I'm sure we can figure it out.

Cheers!