Hi everyone, <div><br></div><div>I would like to comment on the previous discussion about the biogig import of the bdf files, related to the warnings to some triggers. Some of you previously reported that you see </div><div>
the following error messages after importing bdf files with biosig function:</div><div><div>Warning SOPEN: number of event onset (TYP=0) and event offset (TYP=8000) differ (371,366)</div><div>Warning SOPEN: number of event onset (TYP=5A) and event offset (TYP=805A) differ (276,280)</div>
<div>Warning SOPEN: number of event onset (TYP=5B) and event offset (TYP=805B) differ (85,88)</div><div><br></div><div>I recognized that this is due to the "response" triggers. Biosig successfully detects triggers of Stimulus type (first 8 bits of the Status channel) but it is not capable of </div>
detecting the last 8 bits of the Status channel reserved for Response coming mainly from the Switch-boxes.</div><div><br></div><div>That might be the reason why Arno and some other could not replicate this bug, probably because they did not use Biosemi response switch (?). What happens is that biosig somehow detects the Response trigger, but then it marks them as "0s". I know that BioSemi marks the off-set of the response switch (release) and puts "0". </div>
<div><br></div><div>Another reason for the warning might be that when you use response boxes, as well as recording, say, accuracy by looking at the response, and send triggers to eeg machine before the button release, they may add up and give you weird trigger codes. But, the codes are not arbitrary and can be easily converted.</div>
<div><br></div><div>Any comments? Anyone responsible for the Biosig function, could you reply please?</div><div><br></div><div>Best,</div><div>Baris <br>-- <br>SB Demiral, PhD.<br>Department of Psychology <br>7 George Square<br>
The University of Edinburgh<br>Edinburgh, EH8 9JZ<br>UK<br>Phone: +44 (0131) 6503063<br>
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