Total duration of experiment, finite vs infinite instruction presentation

[S. N.]

Hello to everyone.

My first question relates to the total time of my experiment: My E-prime experiment should be run during an fmri session, so I need the exact total duration of the whole experiment (in order to be able to define adequately the sequence protocol for the fmri scanner). Is it okay to use the LogTab "SessionTime" in the Edat-file after running Test Mode or should I calculate it manually?

Second: Have you any recommendations whether it's better to present instruction slides in an fmri experiment for a finite, prespecified duration (as to warrant the synchrony with the scanner pulse) in Eprime, or to give participants the chance to direct reading of instructions self-paced?

Thank you so much in advance!

Best wishes, Sandra

[Paul Groot]

Sandra,

1) You could do this with a short inline script, or just by running the experiment once and use the edat file to manually calculate the time lapse. For example, if you have a waiting screen that continues automatically at the beginning of the experiment when the scanner starts (say WaitMRI), and a goodbye screen at the end (say TheEnd), then just make sure that the following logging is enabled:

WaitMRI.RTTime

TheEnd.OnsetTime

If you also add an inline script after TheEnd, you can add the total time to the output file:

c.SetAttrib "TotalTime", CStr(TheEnd.OnsetTime-WaitMRI.RTTime)

Note that this inline only works if the script and the two objects are at the same level in the object tree. If the objects are at different levels, then you would have to use a global variable to store the start time of the scanner and use that in the subtraction.

2) if your experiment design allows for a fixed duration (i.e. non self-paced), that would be greatly preferred. Regarding instructions: in general you should keep them as short as possible while scanning. Complex experiments should be practiced before scanning so that instructions during scanning can be short reminders. But off-course, not all designs can be practiced beforehand. 

Best,

Paul

--
You received this message because you are subscribed to the Google Groups "E-Prime" group.
To unsubscribe from this group and stop receiving emails from it, send an email to e-prime+u...@googlegroups.com.
To post to this group, send email to e-p...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/e-prime/a0d81b59-ad59-4393-bb99-6c74c62a73dd%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[S. N.]

Dear Paul,

very thank, that's exactly what I needed to know.

Best, Sandra