Have fixation shown for duration if a key is pressed

[David McFarlane]

At 11/5/2009 04:23 PM Thursday, liwenna wrote:
>obviously...
>
>"if triallist.sample > 1 then
>fixationslide.duration = 500 + (2500 - prevrt)fixationslide.duration =
>500 +(2500 - prevrt)"
>
>... should be:
>"if triallist.sample > 1 then
>fixationslide.duration = 500 + (2500 - prevrt)"
>
>On Nov 5, 10:21 pm, liwenna <liwe... at gmail.com> wrote:
> > Hey Cishores,
> >
> > Am I correct to think that you basically want/need to ensure that
> > there is exactly 2,5 seconds + the 'normal fixation time' between the
> > onset of the image and the next cue?

Ah, if that is the issue, might also see 
http://support.pstnet.com/forum/Topic1988-12-1.aspx , sorry if I 
misunderstood that earlier.

-- David McFarlane, Professional Faultfinder


> >
> > How about prolonging the duration of the fixation cross on the NEXT
> > trial with the remainder of the 2.5 seconds?  This way you also won't
> > end your last trial with a fixationcross as you would if an extra
> > fixationcross is added at the end of a trial.
> >
> > I am not entirely sure if my suggestion works (or works right away) as
> > I have no e-prime to try at the moment... but what you could do is:
> > first declare a global variable that will have the response time for
> > each trial written to it so it can be used in the next trial: on the
> > user tab of the script window type "declare prevRT as integer".
> > On your trialproc  you probably have 3 slides: fixationslide, cueslide
> > and imageslide (i am just making up some names now). Insert an inline
> > after the imageslide that writes the response time to the 'prevRT'-
> > variable: if imageslide.rt > 0 then prevRT = imageslide.rt (the 
> first>0 part is to ensure that there actually WAS a response during the
> >
> > imageslide, I don't know what you want the program to do in case of no
> > response... things might actually be done litle different depending on
> > that). Now at the end of the trial the variable prevRT holds the
> > response time on that trial and carries this value over to the next
> > trial, so we can use it to prolonge the fixationslide. I think that
> > that should be possible by placing an inline right before the
> > fixationslide with something like: "if triallist.sample > 1 then
> > fixationslide.duration = 500 + (2500 - prevrt)fixationslide.duration =
> > 500 +(2500 - prevrt)" wherein 500 is my guess at your 'normal'
> > fixationslide duration, the (2500 - prevrt) is rather obvious I hope
> > and the if triallist.sample > 1 part should ensure that the first
> > trial doesn't start with a 3000 ms fixation cross.
> >
> > I think that in order for this to work you should leave the duration
> > on the fixationslide properties tab empty.
> >
> > I hope that this is of some help to you. As said: no e-prime here, so
> > no trying out and no guarantees :) Alternatively it might be possible
> > to use two states on your imageslide, one with the image and one is an
> > 'extra' fixationcross and then have the 2500 ms slide switch states
> > when a response is given, but a) not sure if that works, b) can't make
> > up the code top of my head and c) code would depend on the inputdevice
> > for the response I think.
> >
> > Best regards,
> >
> > liwenna
> >
> > On Nov 5, 7:38 pm, David McFarlane <mcfar... at msu.edu> wrote:
> >
> > > Then I did not follow the description of your experiment, sorry.
> >
> > > -- David McFarlane, Professional Faultfinder
> >
> > > >That makes the image stay on the screen for the duration.  We want the
> > > >fixation image to display for the remainder of the time.
> >
> > > >THanks for the reply.
> >
> > > >On Nov 5, 12:23 pm, David McFarlane <mcfar... at msu.edu> wrote:
> > > > > Try setting End Action to (none).
> >
> > > > > (I just did my own search of the Getting Started and User's Guides,
> > > > > you only learn this in passing deep within Chapter 3 of the User's
> > > > > Guide.  I don't even remember how I learned this myself, probably
> > > > > just pressing all the buttons myself long ago as I continue to do to
> > > > > this day.  This really needs to be better documented.  But I would be
> > > > > glad to be corrected.)
> >
> > > > > -- David McFarlane, Professional Faultfinder
> >
> > > > > >We currently have an experiment when the subject is shown 
> a fixation -
> > > > > >a cue - an image.  They are given 2.5s to respond to the image.  If
> > > > > >they respond before the 2.5s is up we would like the fixation to
> > > > > >display for the remainder of the 2.5s.
> >
> > > > > >Is there an easy way to do this?
> >
> > > > > >Thanks!


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