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Forum Newbie
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Last Login: 2/3/2008 9:33:18 PM
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In my experiment, I have a fixation text display object set to event timing. The next object after this
is a slide (which is also set to event timing). When I specify a prerelease greater than zero (e.g. 100 ms) on the fixation object, I'm noticing something strange happening. In edataaid, it says on about 10% of trials that the onset delay of the
next object (the slide) is -1 ms. For these trials, edataaid lists the offset time of the fixation text object as one millisecond
later (e.g. offset time of 12000 ms) than the onset time of the next slide (e.g. onset time of 11999 ms). Both objects are listed as being on the screen for the correct duration (I calculated this by looking at each object's offset-onset time).
Does anyone know what is going on here? The prerelease is nice because it shortens the onset delay for trials, but the occurrence of this timing irregularity makes me hesitant to use it.
I'm currently running eprime version 1.1.4.1 in windows xp pro.
Thanks
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Forum Newbie
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Last Login: 5/28/2008 4:18:20 PM
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| i have a similar problem (if it is a problem). i get -1 ms onset delays but only for two or three out of 6 pictures displayed one after the other and its always the same pictures with the negative onset delay. the manual says 0-1 ms onset delay is due to rounding up of time values but how do we interpret the -1ms?? anyone?
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Forum MVP
Group: Administrators
Last Login: Today @ 9:12:01 AM
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| A negative -1 value for OnsetDelay is acceptable and will be found when using PreRelease values. The internals of the E-Prime runtime use a precision much higher thatn milliseconds and due to rounding, scheduling, and sync with the vertical blank an OnsetDelay of -1 provides that the system is acting as scheduled. -Brandon
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