Sound onset and response time issues

[David McFarlane]

Zilong,

1) First and foremost, please thoroughly study the "Critical Timing" 
chapter in the User's Guide that came with E-Prime.

2) The RT is relative to the OnsetTime of the E-Object that plays the 
sound, e.g.,
     StimSlide.RT = StimSlide.RTTime - StimSlide.OnsetTime
(do not take my word for that, please look for yourself).  Note that 
the audio hardware may impose additional delays so that actual onset 
of sound lags even further behind OnsetTime, to test this you would 
need additional equipment (e.g., oscilloscope or Black Box Toolkit).

3) Yes, you should be able to trust the RT values even with large 
OnsetDelay values.  But you do well to verify this yourself with 
external testing equipment as mentioned above.

Finally, look at 
https://groups.google.com/d/topic/e-prime/OeiZ00V9SRc for a 
discussion of the various time audit measures.

Best,
-----
David McFarlane
E-Prime training 
online:  http://psychology.msu.edu/Workshops_Courses/eprime.aspx
Twitter:  @EPrimeMaster (https://twitter.com/EPrimeMaster)

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At 8/14/2014 03:34 PM Thursday, Zilong Xie wrote:

>     Hi E-Prime experts,
>      In my experiment, in each trial, I presented a sound and 
> simultaneously collected response to the sound with the slide 
> object. When I checked the edat2 file, I noticed that there was 
> onset delay of about 100 ms (the time scale in the edat2 file is 
> ms, right?) in the slide object. So my questions are:
>    (1) How can I reduce the onset delay of the slide object?
>    (2) Is the RT recorded here relative to the actual onset of the 
> sound or the expected onset of the sound?
>    (3) In the case of large onset delay, can I trust the RT values 
> reported in the edat2 file? And how can I get the actual RT values?
>
>   Thanks!
>
>best,
>Zilong

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