Stim timing adjustment in a continous loop

[Becky Prince]

Hi Mich,

Thanks for the quick response - this is exactly what I needed!

The E-Prime code seems pretty straight forward, but I suppose I wont
know until I get a chance to try it.  You're right about audio
problems in E-Prime, and the timing issues don't help the case for
using E-Prime either.  I'll look into using Pascal for the task
(although I'm hoping that audacity will work as well as the
syntrillium/adobe program for audio editing).  Thanks again, I really
appreciate the help!

Cheers,
Becky

On Feb 9, 3:51 pm, Michiel Spape <Michiel.Sp... at nottingham.ac.uk>
wrote:
> Hi,
> You mean, you use a classical method of adjustment? I made an experiment, I think in 2001 or so, pretty much doing exactly what you want, but with A-B----C------------ rather than B----C, and written in Turbo Pascal. Pascal was already outdated, but still pretty new compared to psychophysiology itself :)
> Anyway,
> 1. YES, you can do that using E-Prime. But it won't be very easy, and probably easier in Pascal
> 2. YES, I did (see above).
> 3. Know that E-Prime isn't brilliant with audio (as I've remarked here before), and audio tones may get cut. This is precisely what would horrify anyone with some psychophysiological training, it certainly does to me. What you might and really should do is:
> - Get syntrillium cooledit 2 (long out of date, called adobe audition nowadays, which is bloated - adobe-style - and doesn't offer much you'll find use for), or any wave-editing tool which offers millisecond time format for convenience.
> - Make ALL intervals, using generate tone and generate silence, like ----A----B--------, ---A------B--------, etc. Make sure to include a constant amount of silence before the first tone and after the second tone. Make sure both tones have a little envelope (fade in/out), to avoid clicks at the beginning and end of the tone. This may feel like an insane amount of work, but it's worth it, because A) you'll know your stimuli, B) you'll achieve 1 / 44.1 (about 0.02) ms timing accuracy (instead of 1 ms). Name them something like 50.wav, 100.wav etc, with each number being the timing.
> - Finally, in E-Prime, use a procedure like this:
> 1. short inline:
>         Dim currentinterval as integer  
>         currentinterval = 1000 'base interval
> 2. Label1
> 3. next inline:
>         c.SetAttrib "soundfilename", cstr(currentinterval) & ".wav"
> 4. SlideDisplay called SlideDisplay1 with duration = infinite, allowable response is {LEFT}{RIGHT}{ENTER}. On the SlideDisplay is placed a text with "Press left to make the interval shorter, right to make it longer, enter if satisfied" and a sound with filename [soundfilename].
> 5. Last inline (sorry for the lack of case, David):
>
>         If SlideDisplay1.Resp = "{LEFT}" then
>                 currentinterval = currentinterval - 50
>                 if currentinterval < 50 then currentinterval = 50 'to avoid 0 interval
>                 goto Label1
>         else
>            if SlideDisplay1.RESP = "{RIGHT}" then
>                 currentinterval = currentinterval + 50
>                 if currentinterval > 2000 then currentinterval = 2000 'to keep a boundary
>            end if
>        end if
>
> Variations, like your looping business can be easily extrapolated from this simple example.
> That's it.
> Cheers,
> Mich
>
> Michiel Spapé
> Research Fellow
> Perception & Action group
> University of Nottingham
> School of Psychologywww.cognitology.eu
>
> -----Original Message-----
> From: e-prime at googlegroups.com [mailto:e-prime at googlegroups.com] On Behalf Of Becky Prince
> Sent: 09 February 2011 13:09
> To: E-Prime
> Subject: Stim timing adjustment in a continous loop
>
> Dear Forum,
>
> I have to create a task where participants hear two tones in a loop
> and adjust the spacing between the tones (that is, they move the
> second tone forward or backward in time) until the participant
> perceives the tones to be rhythmic or isochronous.  We'd like to use
> two keyboard keys as "+" and "-", which when pressed would move the
> second tone forward or backward (say, 50ms) within the continous loop
> of the two tones.
>
> To illustrate, let's say the tones are "A" and "B", and the dashes
> represent some unit of time:
> A---B-----------A---B-----------A---B-----------
> The duration of the loop (from onset of A to onset of A) remains the
> same, but the subject uses two keyboard keys to adjust B until the
> tones sound isochronous:
> A-------B-------A-------B-------A-------B-------
>
> I'm not new to E-Prime, but in the past I've always created standard
> standard probe-response type tasks.  I have not tried to create a
> program like this one before, where the participant has dynamic
> control over the stimuli.
>
> So my questions are the following:
>
> 1) Is it even possible to create this task in E-Prime?
>
> 2) Have you done something at all similar, and if so, how did you do
> it?
>
> 3) If you haven't done anything like this, do you have any ideas about
> how it could work?
>
> My only thought is that perhaps I could set this up so that the two
> tones are not actually 'continous' but presented in pairs over many
> trials, and the temporal properties of trial n would be based on the
> response to trial n-1.  However, I think this would create a delay
> between the end of one 'loop' and the beginning of the next, which
> would certainly affect the subject's perception of a continous
> rhythm...
>
> Any thoughts or suggestions would be greatly apprectiated.
> Thanks!
> Becky
>
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