Task events on EDAT file - E prime 3

[Surya]

Hello,

 

I am starting an experiment which involves sending triggers from the E-prime 3 to an electrophysiology recording equipment (NATUS). I use Task events on E-prime to do this and I am able to view the input triggers on the Trigger channel of the NATUS system. But I am unable to find the trigger data on the E-prime EDAT output file. Could you please tell me where to find the trigger information?

 

Best regards,

Surya Rajan

Research Technologist Sr.

Dept. of Psychological and Brain Sciences

University of Louisville, Kentucky

 

[Spape, Michiel]

Hi Surya,

It seems you are doing everything alright but not quite conceptually grasping trigger synchronisation. With task events, you sent out a trigger to the EEG amp – it’s just a pulse that is sent in synchrony with an external event. For example, you have a stimulus on the screen (e.g. the letter X), to which a participant makes a response as fast as possible, and you want to examine the P3 response to the letter X. In terms of behavior, then, you will want to log the OnsetTime of X, the RT to X – look into the logging options of the stimulus object as these then go into the .EDAT. In terms of EEG, however, you will want the same onsettime of X to appear in the biosignal data, so you use a task-event to send a pulse as soon as X appears (and probably also the RT). Now the .EDAT and biosignal are logged with regards to the same external event, i.e. synchronized.

Does this help?

 

To answer the question more specifically: I don’t know if you can make a task event itself do some sort of logging, but that goes slightly against the idea behind task events anyway: rather the same stimulus that triggers an event-handler should already have been logging into the .edat:

StimulusObject is shown à logs StimulusObject.OnsetTime (turn on in logging)

StimulusObject is shown à starts eventhandler à sends trigger to external equipment

In other words, to log the task event then again would be redundant.

 

Stay safe, E-Prime from home ;)

 

Best,

Michiel

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[Surya Rajan]

Hi Michiel,

Thank you very much the explanation. It really helps and answers my questions.

I had previously used a different software where the trigger itself was logged in the output but yes, it is redundant here given that the trigger data used in the task event is logged in the EDAT file anyway.

Stay safe,

Best regards

Surya

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