Eprime edat Column Header Info

[Ananth Narayanan]

Hello E-Prime experts, 

I am trying to make sense of the .edat file column headers. There are so many that are difficult to read. 

For example I have an ImageDisplay object called Doors. When the paradigm is run, I get the following in the generated .edat2 file. I don't understand how to make sense of this: 

Doors.DurationError: What is this? It ranges between -11 and 1

Doors.OnsetDelay: Also not sure what this is. Ranges between -1 and 11

Doors.OnsetTime: Ranges between 133133 and 509040. Also unsure what this is. 

Doors.RESP: I assume this is the button push. Is either 5 or 6. 

Doors.RT: Ranges between 229 and 2467

Doors.RTTime: Ranges between 133133 and 509413. Also don't know what this is. 

I tried googling it to no avail. PST's knowledge bank also doesn't help me. 

There is another slide called Fixation, and I get the following as columns in the .edat2 file. 

Fixation.DurationError: Ranges between -11 and 1

Fixation.OffsetTime: Ranges between 136634 and 512534

Fixation.OnsetDelay: Ranges between -1 and 11

Fixation.OnsetTime: Ranges between 136145 and 512038

I was not the one who designed this experiment. I have been tasked with analyzing the data. This is an fMRI study, and I am trying to get the onsets and durations for different events so that I can model them appropriately. 

The .txt file is also very cryptic. I would really appreciate it if someone would explain all the terms including, but not limited to, DurationError, OffsetTime, OnsetDelay and OnsetTime etc. 

Thank you. 

'Sincerely,

- Ananth

[David Vinson]

Hi Ananth,

There are short descriptions of all the logged variables if you open your experiment in E-Studio and select Properties > Logging.

RESP is indeed the button push and RT is the RT (msec) from the start of the response-collecting object.   RTTime is the RT measured from start of the experiment; similarly with OnsetTime, it is measured from experiment start. 
Experiment start is not likely to be the same as t0 for your scan(s) in which case you will need to adjust these values by subtracting actual t0 for your fMRI analyses.

DurationError, OnsetDelay and OnsetTime are described in more detail in the E-Prime Users Guide (chapter 4 on critical timing, section 4.6.1).  This pdf can usually be found in the Documentation subdirectory of your E-Prime install and this chapter should be required reading for all E-Prime users.  

The .txt file presents the same information that is summarised in the .edat2 file, just in a line-by-line format. 
If you're handy with scripting it might be easier to extract your onsets etc from the text files

I don't think you'll get a full tutorial of these issues here on the mailing list, but I'm pretty sure timing is covered extensively in the E-Primer textbook
http://www.e-primer.com
and it is definitely covered in David McFarlane's online course,
http://psychology.msu.edu/Workshops_Courses/eprime.aspx

all the best,
David V

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[Ananth Narayanan]

Thank you, David, for pointing me in the right direction. These really help me out.

'Sincerely,

- Ananth

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