randomly alternating between two SlideStates

[liwenna]

Hi Erin,

So... how did you do this randomization within a triallist in the
older set-up?
Because I personally would rather use a list-based randomization than
two slidestates.

If you have a triallist in which both the attributes match and foil
are defined than you'll have 'match and foil' pairs as the same match
and foil will always be shown together.

Now... if you into that triallist nest a second list called something
like randompositions and in that list create two attributes called...
xposmatch and xposfail you can enter the values of the x (i.e. 25% and
75% vs 75% and 25% on the second level) into these cells, set that
list to random and you're set. Although you should manipulate the
weights a bit as randomizing two values (two levels) doesn't give much
variation. Giving both levels a weight of 2 or 3  solves that. Make it
so that the total trials within each block or the entire experiment is
a multitude of the total 'draws' from the randompositionslist, in
order to have complete randomization.

If you rather use the two slidestates, which is actually as fine a
solution... then don't create a list called something like
randompositions but rather nest a list called randomstate. In this
list create one attribute called 'statename' (or something the like),
and in the cells enter the values 'MatchLeft' and 'MatchRight'. Again,
a randomization on 2 draws doesn't give much variation so manipulate
the weights. Set this list to 'random' on the slide set the slidestate
to [statename] and you're set.

Best,

liw

On May 13, 2:40 am, Erin <erin.sieb... at gmail.com> wrote:
> Hello,
> I have a question about randomizing image placement, by randomly
> displaying one of two Slidestates in each trial of my experiment.
> Right now I have a slide in my experiment with 2 SlideImages, which
> are named [match] and [foil],  at the right and left of the screen. I
> would like the match and foil image to randomly appear within either
> the right or left SlideImage, in a random fashion. I made two
> SlideState tabs in my slide, named MatchLeft and MatchRight, which
> reverse the location of [match] and [foil].  I would like to randomly
> use one of these two slide states for each trial.
>
> I looked at the "NestingRT" randomizing example program, and this is
> on the right track. However, I want to clearly define each trial, so
> that the same individual match and foil image always appear paired
> together within the same trial. The only thing I want to randomize is
> whether the match and foil appear on the right or left.
>
> Originally, I had the experiment set up with with the two slide images
> named [leftimage] and [rightimage], and randomized the right and left
> placement of the match and foil images in the triallist. However, this
> is very impractical, as we are planning to do very large numbers of
> trials, and need the right and left placement of sample and foil to be
> independently randomized for each subject and session.
>
> Any help or pointers would be very much appreciated.  Thank you
>
> Erin

-- 
You received this message because you are subscribed to the Google Groups "E-Prime" group.
To post to this group, send email to e-prime at googlegroups.com.
To unsubscribe from this group, send email to e-prime+unsubscribe at googlegroups.com.
For more options, visit this group at http://groups.google.com/group/e-prime?hl=en.