Response triggers with accurate timing

[RB209]

Hi,

I have been struggling to send triggers to Actiview at the exact time
a participant makes a response.

I'm running a memory experiment where images are presented in a slide
object and participants respond by pressing 1,2,3 or 4. I would like
triggers to be sent a.) at the onset of the slide and b.) at the exact
point a participant makes a response. I want the slide to run for
2500ms but responses to be collected for 3700ms in total. (Slide1 is
followed by a blank screen for 1200ms).

The first issue is fine. I use ...

slide1.onsetsignalenabled = true
slide1.onsetsignalport = &H378
slide1.onsetsignaldata = &H05 'send 5 so the value does not clash with
a possible response.
sleep (10)
writeport, &H37, 0

However, I can't get the response trigger to send accurately. I have
been trying to use slide1.inputmasks.Ispending to collect the
participant's response and writeport it while the slide is presented.
Unfortunaltely, this sends the trigger late (looks like it is being
sent after slide1 has finished running). This remains the case even if
I set the slide1 duration to 0 . I have also tried setting the slide
duration in properties to 2500 and using a large prerelease on the
slide object. This seems to send the response triggers on time
although I'm only judging this by eye at the moment. However, it
causes problems with data logging in eprime. I.e Eprime only logs
about 30% of the responses unless I reduce the prerelease. Also, no
matter what I try I seem to either get stimulus onset triggers OR
response triggers but not both. (I am sending 0s after each trigger to
clear everything but still having problems).

I would appreciate any help with this issue - I have honestly been
trying for days to sort this by myself. I have found previous
discussions useful and have looked at some of the sample experiments
but I still haven't gotten close to solving this problem. I am able to
achieve most of the subtasks but cannot put them together in a way
that works.

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