Task Events - Sending multiple triggers at the same time?

[leonie.balt...@gmail.com]

Hi,

I am using Task Events to send triggers to an EEG recording system (ANT Neuro system) through a parallel port. 

I am trying to send different triggers at the exact same time however only some of the triggers are being recorded. For example: I send an '100' for Fixation.Onset and the condition number (which can vary from 1 to 32). So I should receive the trigger '100' and for example '23'. I wonder if I am doing something wrong? I put the signal value back to zero after 50ms.

My question is: Is it possible to send multiple triggers at the same time for the same event?

Many thanks! Leonie

[David McFarlane]

Leonie,

Suppose you set up the following Task Events:
Fixaton.OnsetTime
- Delay: 0
- Action: WriteByte
- Custom: 100
Fixaton.OnsetTime
- Delay: 0
- Action: WriteByte
- Custom: 23
Fixaton.OnsetTime
- Delay: 50
- Action: WriteByte
- Custom: 0

This will *not* work well. This would try to output "100" and "23"
simultaneously on the same channel. It would be like writing down "I
love you", and then overwriting that with "I hate you" -- the final,
combined written message would look garbled, sort of like "I lhoavte
you", except with the letters actually overlapping.

Suppose instead you meant to do this:
Fixaton.OnsetTime
- Delay: 0
- Action: WriteByte
- Custom: 100
Fixaton.OnsetTime
- Delay: 50
- Action: WriteByte
- Custom: 23
Fixaton.OnsetTime
- Delay: 100
- Action: WriteByte
- Custom: 0

That should work, you should get two signals just 50 ms apart, which may
be good enough.

Hope that helps.
---------------
David McFarlane
E-Prime training online:
http://psychology.msu.edu/Workshops_Courses/eprime.aspx
Twitter: @EPrimeMaster (https://twitter.com/EPrimeMaster)

[Leonie Balter]

Thanks for your fast response and clear explanation. If I set the signal value back to zero after 50ms for one and for the other after 100ms, this also means that the trigger is being sent 50ms later? Can I also use a delay of 10 for one trigger and 50 for the second trigger? (I use a sampling rate of 500Hz).

I will immediately try it tomorrow!

On 2016-08-30 11:40 AM, leonie.balter.bioactor@gmail.com wrote:

I am using Task Events to send triggers to an EEG recording system (ANT
Neuro system) through a parallel port.
I am trying to send different triggers at the exact same time however only
some of the triggers are being recorded. For example: I send an '100' for
Fixation.Onset and the condition number (which can vary from 1 to 32). So I
should receive the trigger '100' and for example '23'. I wonder if I am
doing something wrong? I put the signal value back to zero after 50ms.
My question is: Is it possible to send multiple triggers at the same time
for the same event?

Many thanks! Leonie

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Leonie Balter

Trainee

E: leonie.balt...@gmail.com | I: www.bioactor.com

A: Biopartner Center | Oxfordlaan 70 | 6229 EV Maastricht | The Netherlands

[David McFarlane]

Leonie,

Ah, your response reminds me that I made a mistake there! Try something
more like:

Fixaton.OnsetTime
- Delay: 0
- Action: WriteByte
- Custom: 100
Fixaton.OnsetTime
- Delay: 50
- Action: WriteByte

- Custom: 0

Fixaton.OnsetTime
- Delay: 100
- Action: WriteByte

- Custom: 23
Fixaton.OnsetTime
- Delay: 150

- Action: WriteByte
- Custom: 0

You see, I neglected to reset the output to 0 before outputting the
second signal! I fixed that in the above, so that now it would output
the first signal at the OnsetTime, then 50 ms later reset the output to
0, then 50 ms after that output the second signal, and another 50 ms
later reset the output to 0 again. So as you said, the second signal
actually gets output 100 ms after the OnsetTime.

And yes, you might titrate the delay values to see what works with your
equipment. With some equipment I have seen delays as short as 1 ms
work. 10 ms delays seems like a good starting point.

-- David McFarlane

[Leonie Balter]

Hi David,

I tried your suggestions today and everything works perfectly now. Thanks!

Leonie

On 2016-08-30 11:40 AM, leonie.balter.bioactor@gmail.com wrote:

I am using Task Events to send triggers to an EEG recording system (ANT
Neuro system) through a parallel port.
I am trying to send different triggers at the exact same time however only
some of the triggers are being recorded. For example: I send an '100' for
Fixation.Onset and the condition number (which can vary from 1 to 32). So
I
should receive the trigger '100' and for example '23'. I wonder if I am
doing something wrong? I put the signal value back to zero after 50ms.
My question is: Is it possible to send multiple triggers at the same time
for the same event?

Many thanks! Leonie

--
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