GENERAL: Object Execution [22853]

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    David McFarlane

    This article says, "An object’s execution occurs from its StartTime until its StopTime."  In fact, there is no StopTime property -- I suspect you mean FinishTime.

    The article then goes on to say, "The duration of an object’s execution is the difference between the OffsetTime and the OnsetTime."  This statement explicitly conflicts with the earlier statement.

    The correct statement would be, "The duration of an object’s execution is the difference between the FinishTime and the StartTime", although that is hardly a value that users care about explicitly, but do care about in relation to PreRelease.

    By contrast, the difference between the OffsetTime and the OnsetTime simply provides the duration from the onset action of an object to its offset action, yet another value that users hardly care about.

    Users do care about the actual duration of presentation of a visual object, which, as the article says, is given by OnsetToOnsetTime (i.e., the difference between the OnsetTime of the following object and the OnsetTime of the current object).  Although this also assumes that ClearAfter is set to false, otherwise the duration of presentation would come to OnsetTime - OffsetTime, which could result in surprises when using PreRelease (thus ClearAfter is now deprecated).

    Please see also https://groups.google.com/d/topic/e-prime/OeiZ00V9SRc.

    I suspect this article has many more errors.  To be fair, it is hard to express all these timing issues correctly (I speak from experience).  Users should be wary of trusting this article.

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