Have fixation shown for duration if a key is pressed

[liwenna]

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?

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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