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<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=470345312-03072002>Steve,</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=470345312-03072002></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=470345312-03072002>There
are a number of ways to do this, but I think the easiest is to add an
Inline object after the stimulus presentation with the following single line
of script on it.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=470345312-03072002></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=470345312-03072002> ' Assume the object named
Stimulus is presenting the stimulus and enabling the
response. </SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=470345312-03072002> ' The Stimulus object should
have ClearAfter=yes and OffsetSync=yes (which are not the
defaults)</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=470345312-03072002> SetNextTargetOnsetTime
(Stimulus.OnsetTime + Stimulus.Duration) ' add
Stimulus.Duration if appropriate or another value equal to the time you want
between stimulus presentations</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=470345312-03072002></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=470345312-03072002>The
SetNextTargetOnsetTime command allows you to directly
manipulate when the next stimulus object to run should present it's
stimulus. The Stimulus.OnsetTime property returns the time (in ms)
when the stimulus was actually presented. Thus, if you use that time
and add a duration equal to an entire trial length then the next object to run
(presumably the Stimulus object of the NEXT trial) then your critical stimulus
should occur at fixed intervals.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=470345312-03072002></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=470345312-03072002>Depending on the exact nature of your stimulus sequence
you should probably consider using Timing Mode=Cumulative (see the E-Prime
documention on Critical Timing), but if they only thing you have in your trial
is the Stimulus object itself then the above line of script effectively
simulates what the Cumulative timing mode is trying to do. If you
have a sequence like Fixation, Probe, Mask and you want to keep a fixed trial
duration and fixed inter-trial-interval then you should really look
into cumulative timing mode.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=470345312-03072002></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=470345312-03072002>To
verify the above script is working correctly I would make sure the Stimulus
object is logging OnsetTime and OnsetDelay and then use E-DataAid to
view those two columns. Copy the data to Excel and subtract the
Stimulus.OnsetTime of trial n+1 from Stimulus.OnsetTime of trial n, i.e. to
compute the time between the stimulus presentations. If things are
setup correctly then these should times should be within 1 screen refresh
of the desired duration.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=470345312-03072002></SPAN></FONT> </DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=470345312-03072002>Hope
that helps.</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN
class=470345312-03072002>Tony</SPAN></FONT></DIV>
<DIV><FONT face=Arial color=#0000ff size=2><SPAN class=470345312-03072002>
<P><FONT face="Courier New" size=2>*** DISCLAIMER: VIEWS EXPRESSED ARE MY OWN
AND DO NOT</FONT> <FONT face="Courier New" size=2>NECESSARILY</FONT> <FONT
face="Courier New" size=2>REFLECT THOSE OF MY EMPLOYER ***</FONT> <BR><FONT
face="Courier New" size=2>Anthony P. Zuccolotto</FONT> <BR><FONT
face="Courier New" size=2>Vice President of Operations</FONT> <BR><FONT
face="Courier New" size=2>Psychology Software Tools, Inc.</FONT> <BR><FONT
face="Courier New" size=2>2050 Ardmore Boulevard</FONT> <BR><FONT
face="Courier New" size=2>Suite 200</FONT> <BR><FONT face="Courier New"
size=2>Pittsburgh, PA 15221-4610</FONT> <BR><FONT face="Courier New"
size=2>Phone 412-271-5040</FONT> <BR><FONT
face="Courier New" size=2>FAX
412-271-7077</FONT> <BR><FONT face="Courier New"
size=2>Email anthony.zuccolotto@pstnet.com</FONT>
<BR><FONT face="Courier New" size=2>Internet <A
href="http://www.pstnet.com/" target=_blank>http://www.pstnet.com/</A></FONT>
</P></SPAN></FONT></DIV><FONT face=Arial color=#0000ff><SPAN
class=470345312-03072002></SPAN></FONT><FONT face=Tahoma>
<DIV><FONT face=Arial color=#0000ff size=2></FONT><FONT face=Arial color=#0000ff
size=2></FONT><BR><FONT size=2><SPAN
class=470345312-03072002> </SPAN>-----Original Message-----<BR><B>From:</B>
Steve Johnston [mailto:s.johnston@bangor.ac.uk]<BR><B>Sent:</B> Wednesday, July
03, 2002 5:04 AM<BR><B>To:</B> Eprime Maillist<BR><B>Subject:</B> Constant
timing for targets<BR><BR></DIV></FONT></FONT>
<BLOCKQUOTE dir=ltr
style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px solid; MARGIN-RIGHT: 0px">
<DIV><FONT face=Arial size=2>I've happily set up an experiment to show a
stimulus to a subject, but at the moment once the user responds the next
sequence begins immediately. What I was after was, once a target had been
responded to, an empty screen for the remainder of the period such that the
period between fixation points was a constant.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Does anyone know how to set this up? I have
played with the various settings but so far no joy.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Cheers</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Steve
Johnston</FONT></DIV></BLOCKQUOTE></BODY></HTML>