online trigger of keybaord responses

[Don.Rojas at UCHSC.edu]

David,
 
We tried this in our own MEG system and were never successful with
respect to accuracy.  The keyboard itself is terrible enough with
timing, but then the problems you mention emerge.  What response device
are you using?  I'd think not an actual keyboard in the shielded room -
perhaps you use the Lumitouch optical device that maps to the keyboard?
If so, what we did was have our engineer directly map that device to the
MEG external stimulus/response inputs, while preserving the keyboard
mapping for eprime.  I don't think you'll ever be able to achieve what
you want while still preserving accurate timing, but let me know if you
think of another clever solution.
 
Don Rojas, Ph.D.
Neuromagnetism Laboratory
U. of Colorado Health Sciences Center
Denver, CO 80220

	-----Original Message-----
	From: eprime at mail.talkbank.org [mailto:eprime at mail.talkbank.org]
On Behalf Of David Hairston
	Sent: Wednesday, August 02, 2006 10:36 AM
	To: EPRIME at mail.talkbank.org
	Subject: online trigger of keybaord responses
	
	

	I would like to get an externally triggered record of a keyboard
press for use with an MEG system.

	Is there a way to get a time-locked onset signal or "trigger" of
a keyboard/mouse response at the time it is made, similar to the
.OnsetSignalEnabled property for runnable objects, even if the current
object is still executing?

	Ideally I'd like to have access to the accuracy of said
response, evaluate it and send an external digital signal signifying
this... but just getting a signal out at all would be workable.

	 

	I know it can be done easily AFTER the target object has
occurred, for example something like "if rresponse.ACC = 1 then
WritePort &378, 1".

	However, this is only (relatively) time-locked w/ the response
in the case where the response terminates the object; in the case of a
fixed-duration with recorded response, the evaluation/trigger would not
occur until afterwards, and hence somewhat later than the actual
response time.

	 

	Does anybody have some insight on a trick to get this?

	Thanks

	 

	 

	 

	W. David Hairston, Ph.D.

	ANSIR Lab

	Dept of Radiology

	Wake Forest University School of Medicine

	Medical Center Blvd

	Winston-Salem NC 27157

	(336) 716-7160 (Offiice)

	(336) 716 0798 (Fax)

	 

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