E-prime 2 -trigger

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DSanabria
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Joined: Mon May 05, 2014 7:33 pm

E-prime 2 -trigger

Post by DSanabria » Mon May 12, 2014 10:09 pm

I'm new to BIOSEMI and I'm just about to start an experiment using E-prime 2 Professional. I'm using the Task Event feature in E-prime, sending inputs through the parallel port.


I have used the task "writebyte" so far , and I can see the triggers tags in the "status" channel in Activeview. However, I can see that few ms before the tag, the "Status" channel shows activity, falling and then rising just before the tag. What I want to be sure is that the tag correspond to the time where the display computer is sending the input, i.e., to the onset of the stimulus that sends the trigger.

should I use the task "setbit" at the moment of the stimulus onset, i.e., set the pin to "high", and then "resetbit" at the end of the stimulus, i.e., set the pin to "low"?

thanks

Coen
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Re: E-prime 2 -trigger

Post by Coen » Tue May 13, 2014 1:58 pm

Use the "analog" display mode for the triggers (colored bar for each separate trigger line). Program E-prime/Presentation as follows:

- all 8 or 16 trigger lines/bits should be normally Low (not visible in ActiView)
- on a stimulus onset, the appropriate trigger lines/bits should go High (colored bars show up in ActiView)
- all 8 or 16 trigger lines/bits should return to Low before the next stimulus.

Best regards, Coen (BioSemi)

psdc
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Joined: Thu May 14, 2015 4:26 am

Re: E-prime 2 -trigger

Post by psdc » Thu May 14, 2015 8:21 am

I'm a little unclear what this means as far as the relationship between what I set in my stimulus presentation software and what I set in ActiveView.

At the moment (speaking binary) I set trigger 1 as 11111110 at onset and 11111111 at offset (this is what it shows in Binary setting in LabView). Is what your saying is that I should set all channels to 00000000 at the start of the experiment and then set the trigger as 00000001 onset and return to 0 at offset?

Coen
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Re: E-prime 2 -trigger

Post by Coen » Thu May 14, 2015 11:15 am

Yes, exactly, return all lines to zero between the triggers.

With your current setup (inverse logic) some of the triggers can remain invisible in the ActiView display, and you may loose triggers on file when down-sampling is applied.

Best regards, Coen (BioSemi)

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