response event to writeport oddities

[andrew hill]

hi folks,

any chance this makes sense to someone?  i've been pulling my hair out metaphorically for a bit on this.

i've got a trial procedure that mimics a typical CPT, e.g. an ImageDisplay that shows either a distractor or a target for 50ms, and then a fixation slide for most of the trial. in more detail:

TrialProc:
----------------------
InLineStimMarker 
InLineResponse 
ImageDisplay (shows a stimulus requiring response or a distractor requiring nonresponse)
InLineFixDuration (Fixation.Duration = random(950,1450)
Fixation

The InLineStimMarker does a :

WritePort &H378, 0
ImageDisplay.OnsetSignalEnabled = True
ImageDisplay.OffsetSignalEnabled = True
ImageDisplay.OnsetSignalPort = &H378
ImageDisplay.OffSignalPort = &H378

and then a bunch of loops looking up a c.GetAttrib to figure out what the current stimulus type is, and set OnsetSignalData to a numerical value. this works great - sending in the codes as appropriate to BioSemi ActiveTwo, at the onset of each stimulus.   

the problem is with InLineResponse, which I've tried putting various places, and tried various code.

what I want to do is look up the response accuracy, and put it in the EEG record at the time of the response.  of course, since this is a CPT, most of the trials don't have a response, which is ok.  

the ones that do require pushing a keyboard button, and i'd like to code a 100/200 response accuracy into the EEG record when that button is pushed, but i'm not having any luck at all.

i've tried something like this:

If ImageDisplay.ACC = "1" Then
Writeport &H378, 100
else
Writeport &H378, 200
end if 

but that just puts the 100/200 codes at the time of stimulus image, and not at/during the response.

any suggestions?

thanks,
andrew

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