Hello everyone,
In my experiment, EEG data will be collected during a modified version of the Stroop task. The trial start with a warning/cue stimulus followed by a target stimulus with two conditions (congruent and incongruent). Subject responds to the target stimulus (correct and incorrect). My question is, How can I get the event markers for all of this information (warning stimulus onset, target stimulus onset, stimulus condition, respond condition) and attach these event markers to the continuous EEG data using EEGLAB to start the pre-processing analysis procedures?
Thank you,
In E-prime, you must explicitly select all the event-times that you want in your output tables. To do so, for each event of interest, you must select "logging" among its properties and then check all the items you want (e.g., onset time, onset delay, ACC, RT, are always useful).
When you have all your onsets, if your EEG + behavioral acquisition was synchronized with at least a trigger, you can match each time of interest (e.g., each onset time) with the EEG-related activity.
Simone
First off, I am afraid that at least on E-Prime 2.0 professional (which is what we got in our lab) there is no such a thing as an "output file" for event-code triggers. You have to communicate the PC where E-prime is running with the interface of your EEG system (e.g. Biosemi actiview) and through that to the PC that is recording the EEG data. This communication in our case is made by means of a presentation cable connected to a LPT1 port on the output PC that inputs to a 37 Pin connector on the EEG system interface.
You have two ways to send event codes Triggers in E-Prime:
1. Using the "Task Events" function. See some of the following material for further explanation:
https://www.youtube.com/watch?v=0oxtfdZb0Fo
https://support.pstnet.com/hc/en-us/articles/115015040608-GENERAL-Configuring-Task-Events-24789-
https://support.pstnet.com/hc/en-us/articles/229350487-E-Prime-How-To-Task-Events
2. Using In-Line scripts. This seems difficult to do at first glance, but actually is relatively simple once you get the idea. A kind soul published several years ago some material that is still useful on this regard:
https://magnuson.psy.uconn.edu/wp-content/uploads/sites/1140/2015/01/mr2006-01_eprime_eeg.pdf
Please consider which is your port address first and change what is needed in the user script to make it works right (especially if you are using Windows 8/10).
A third alternative pathway to write event codes I guess could be by means of creating an Event List file manually in the ERPLab plug-in on EEGLab including the onset times for the cue/warning and Targets events as registered in the .edat file from E-Prime. I never have tried to do that with this specific purpose, but I imagine that in the long way it could works fine. Please be aware that this only would be right if your EEG recording started at the very same time than the experiment started running on E-Prime.
Hello Mohamed Aly , I have also similar kind of problem. Have you found any solution for it ?
I have records of EEG from 4 channels of 'Bioradio' device. It has the output value of the voltages value. I am trying to process the data in ERPLAB. I am going through the videos tutorial of ERPLAB. I can import the data and look how the plots seems like. But when I reach the part to create an EVENTLIST, there seems to be a problem 'No event codes'.
I have visual stimulus. It shows standard and rare stimuli without any user response. I know the rare stimuli counts as event codes. But how do I add event codes ? How do I proceed from here ?
Hello Rasa Bhattarai,
To create an event list you have to make sure that the events were already imported.
Several ways can be used to attach the event markers to EEG data. It actually depends on the way that you collect your data. For example, the event markers in my data were recorded by an external channel (sensor attached to the screen can read the stimulus onset and offset). So I used that channel to insert the events to raw EEG data.
EEGLAB > File > Import event Infro > from data channel.
Another way, you can use the output file from the program that you used to present the stimulus (such as e-prime, and super-lab,.etc). The output file from these programs may include all the information that you need to attach the event codes to your data.
EEGLAB > File > Import event Infro > From E-prime ASCII (text) file.
Hope that will help.
Hello Mohamed Aly ,
Thanks a lot for sharing this info. I got more understanding after searching about it. I am still working on it.
For my experiment, I have no user response when I show visual stimulus. The experiment shows a 'red' ball in random place on the screen for most of the time and after let's say 4 seconds, the ball changes it's color to 'blue' for 2 seconds and back to 'red' for 4 seconds . I run the experiment for 10 seconds. Now, we can consider the red ball as standard and blue ball as rare stimuli. I believe the event codes can be any indicator like 0, 1 etc.
So for this experiment, I need to assign 1 as the event code when ball appears blue. Am I right in my understanding ?
Also one more thing, the Bioradio device that I am using shows the output of EEG voltages as cell array {1,1}, {1,2} etc. I am struggling with the matlab script that would add event code as 1 when the ball appears blue. How do I add the event code corresponding to that particular EEG voltage from '0' when standard stimuli is shown and '1' when rare stimuli appears ?
Do you have any knowledge regarding this ?
Rasa Bhattarai, I am wandering, what software did you use to show the visual stimuli?
Mohamed Aly , I have used Psychtoolbox for preparing visual stimulus. I have Bioradio device for recording EEG. It is compatible only with MATLAB so I choose to make my stimulus in MATLAB.
Any suggestions on my query ?
Rasa Bhattarai, You may need to check the time for each stimulus and put the event markers manually or in a text file and then import that file using EEGLAB (you should be very precise). This way can work if you have the onset and duration of each stimulus/trial, and also recording EEG data should be synchronized with the stimulus presentation.
Mohamed Aly , Yes, actually to be very precise is what I am afraid of if I do it manually. It needs to be accurate so I want to write a script which would simultaneously record the event codes in the program along with the exact time and the voltage value.
Anyways, thank you for your suggestions. It was helpful.
- Badges
- Science topic