User`s guide

E-Prime User’s Guide
Chapter 3: Critical Timing
Page 107
The Data Logging property in the object’s Property pages (Duration/Input tab) sets the options as
to what data will be logged in the data file. For an object performing time-critical presentation but
not collecting a response, select Time Audit Only. This logs the OnsetDelay, OnsetTime, and
DurationError measures for the object. The Data Logging setting of Standard collects Time Audit
values as well as subject response variables (e.g., the dependent measures of RT, RTTime,
ACC, RESP, CRESP).
Figure 18. The Logging tab of an object’s Property pages with the Data Logging
Property set to Standard on the Duration/Input tab.
The next table shows the typical output from a run of the experiment TimingParadigm2.es and
analyzing the data in E-DataAid
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. The OnsetDelay is the delay between when the object began
watching for the onset synchronization event (e.g., vertical blank) until the event occurred and the
display was written to the video card. This should range from –1 up to the duration of a single
refresh (e.g., approximately 17ms in this example)
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. If this number is beyond the duration of a
single refresh, then the setup activities must have delayed the waiting for the vertical blanking
code. In this example, all of the OnsetDelay values were in the expected range.
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The Timing paradigm experiments are available from PST at http://www.pstnet.com. The timing tables
created for this text can be created with E-DataAid in a few minutes. After you load the data file into E-
DataAid, use the Tools menu option and choose Arrange Columns. Use the Select box to enter a wildcard
of “block;*delay;*time” (using a “;” separator). Click Select and then click the Add button. If you analyze the
results from TimingParadigm2, you should see a table very similar to the one above except for the last two
columns. The data may be copied to the clipboard (Ctrl-C) and pasted into Excel. The last two columns are
calculated using Excel formulas. The Fix-Probe time is the Probe.OnsetTime minus the Fixation.OnsetTime.
The Probe-Mask time is the Mask.OnsetTime minus the Probe.OnsetTime.
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E-Run permits the search for the vertical blanking signal to begin 1ms before the targeted time, so it is
possible to have an onset delay of –1ms. This allows the system slightly more time to get ready for the
upcoming display.