E-prime and skin-conductance response experiments

[Paul Gr]

hi rachel,

you will require a special isolation module (STP100C) for the biopac
configuration to be able to (safely) connect the stimulus PC to the
acquistion hardware. (http://biopac.com/product.cgi?type=view&item=STP100C)
Since a few months, BioPac also offers the correct interface cable to
connect this module to a printer port.

After the hardware is setup, you should use some inline EPrime script to
send the digital triggers to the LPT port. There are two options:

1) insert some inline script somewhere before the object that will generate
onset and reset codes. In this example the object is called 'mystim':

' for the onset (code 255 as example):
mystim.OnsetSignalEnabled = True
mystim.OnsetSignalData = 255
mystim.OnsetSignalPort = &H378  ' default address of LPT1
' to reset:
mystim.OffsetSignalEnabled = True
mystim.OffsetSignalData = 0        ' just reset all bits
mystim.OffsetSignalPort = &H378

2) Use the WritePort command to send digial values:
WritePort &H378, 255
...
' and at a later point:
WritePort &H378, 0 ' to reset all bits

Option 2 is a bit tricky when you also use so called PreRelease intervals,
which could change the start time of your script and lead to unexpected
trigger times.

Also note that the values you send to the LPT port should be stable for at
least the sampling interval time used on your biopac configuration. (I.e.,
don't reset the bits within 4 msec if you sample at 250Hz)

Just another thing: skin conductance responses need some time to 'relax'
after a stimulus, so don't make you stimulus-to-stimulus time too short.

hope this helps.

Paul Groot
Vrije Universiteit Amsterdam
ITM-FPP
(see also http://www.psy.vu.nl/download/menu/)



>From: "Rachel Mitchell" <r.l.c.mitchell at reading.ac.uk>
>To: "Eprime mailing list" <eprime at mail.talkbank.org>
>Subject: E-prime and skin-conductance response experiments
>Date: Tue, 25 Jan 2005 10:56:42 -0000
>
>Hi everyone
>
>Does anyone use E-prime in conjunction with SCR recording equipment (either
>biopac or psylab)
>
>I've been asked a question about e-prime/SCR recording that I thought
>someone might know the answer to....
>
>'is it possible to have E Prime send a signal to the PC recording SCR when
>a
>new block of text is presented or when a response to a question is made'
>
>stimuli are presented visually (rather than auditorily)
>responses are mouse clicks
>
>Regards
>Rachel
>
>-----------------------------------------------------------------------
>Dr Rachel L. C. Mitchell
>Lecturer in Cognitive Psychology, University of Reading
>Honorary Research Fellow, Institute of Psychiatry
>Research Psychologist, Berkshire Healthcare NHS Trust
>
>Correspondence Address:
>School of Psychology
>Whiteknights Road
>University of Reading
>Reading
>Berkshire
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>
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