2.11: Review of Processing Steps

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You did a lot of exercises in this chapter, and they’re probably beginning to blur together in your mind. So let’s review the steps:

Load the EEG dataset
- EEGLAB > File > Load existing dataset
Look at the dataset to verify that the EEG and event codes looked okay
- EEGLAB > Plot > Channel data (scroll)
Filter out the low-frequency drift in the EEG
- EEGLAB > ERPLAB > Filter & Frequency Tools > Filters for EEG data
Add an EventList to the dataset
- EEGLAB > ERPLAB > EventList > Create EEG EVENTLIST
Verify that we had the correct number of occurrences of each event code
- EEGLAB > ERPLAB > EventList > Summarize current EEG event codes
Use BINLISTER to assign events to bins
- EEGLAB > ERPLAB > Assign bins (BINLISTER)
Extract fixed-length epochs from the continuous EEG and perform baseline correction
- EEGLAB > ERPLAB > Extract bin-based epochs
Test each epoch for artifacts using a simple voltage threshold, verify that the appropriate epochs were marked, and see how many artifacts were detected
- EEGLAB > ERPLAB > Artifact detection in epoched data > Simple voltage threshold
Average together the epochs without artifacts, separately for each bin
- EEGLAB > ERPLAB > Compute averaged ERPs
Plot the averaged ERP waveforms
- EEGLAB > ERPLAB > Plot ERP > Plot ERP waveforms
Examine the data quality of the averaged ERPs
- EEGLAB > ERPLAB > Data Quality options > Show Data Quality measures in a table

Although this may seem like a lot, it’s the minimal set of steps for going from raw EEG to an averaged ERP in ERPLAB for most studies. There are many additional steps that are often included in what we call the EEG preprocessing pipeline, and there are also many steps after averaging. Indeed, several preprocessing steps had already been applied to the EEG data used in this chapter’s exercises. That’s why I decided to write a whole book! I hope this chapter has given you a clear overview of the basics of EEG preprocessing. The next chapter will show the basic steps that follow the creation of the averaged ERP waveforms.