Initial session error

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emily
Posts: 40
Joined: 24 Mar 2008, 06:13

Initial session error

Post by emily » 05 Feb 2009, 21:26

Hi Gerv,
When running the initial session with neuroscan I'm getting the following error.

Warning: StimulusPresentationTask::Preflight: Due to a sample block duration of 40ms, the actual value of the ISIMaxDuration for stimulus 1 will be 1480ms rather than 1500ms.
Warning: StimulusPresentationTask::Preflight: Due to a sample block duration of 40ms, the actual value of the ISIMaxDuration for stimulus 2 will be 1480ms rather than 1500ms.
Warning: StimulusPresentationTask::Preflight: Due to a sample block duration of 40ms, the actual value of the ISIMaxDuration for stimulus 3 will be 1480ms rather than 1500ms.
Warning: StimulusPresentationTask::Preflight: Due to a sample block duration of 40ms, the actual value of the ISIMaxDuration for stimulus 4 will be 1480ms rather than 1500ms.

Any idea how to fix this?

Thanks,
Emily

gschalk
Posts: 615
Joined: 28 Jan 2003, 12:37

Neuroscan ...

Post by gschalk » 05 Feb 2009, 21:41

Emily,

Simply set the ISIMin/MaxDurations to 1480ms.

This warning is because the Neuroscan system (and thus BCI2000) is set to a fixed SampleBlockSize of 40 at 1 kHz (40 ms). Thus, the timing in BCI2000 is driven by a 40 ms clock, and 1500 ms is not a multiple of 40ms.

Gerv

emily
Posts: 40
Joined: 24 Mar 2008, 06:13

ISI field

Post by emily » 16 Feb 2009, 18:18

Hi Gerv,
Thanks for getting back to me so quickly. I can't find an ISI field under any of the configuration tabs. Is it known by any other name?
thanks,
Emily

gschalk
Posts: 615
Joined: 28 Jan 2003, 12:37

ISIMinDuration

Post by gschalk » 16 Feb 2009, 20:41

Emily,

These parameters are named ISIMinDuration and ISIMaxDuration in BCI2000 v2.0. They are in the Application tab and are described on http://www.bci2000.org/wiki/index.php/U ... tationTask

Gerv

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