2: Processing the Data from One Participant in the ERP CORE N400 Experiment
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Learning Objectives
In this chapter, you will learn to:
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Load
EEG
data
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Create an
EVENTLIST
, which stores information about events such as stimuli and responses
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Assign events to bins with
BINLISTER
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A
bin
is a set of ERP waveforms, one for each channel, that were created by averaging together a set of trials
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Parse the continuous EEG into a series of discrete epochs (e.g., from -200 to +800 ms relative to stimulus onset) and perform baseline correction
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Perform simple artifact rejection
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Compute and plot averaged ERP waveforms
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Filter EEG and ERP data
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Make difference waves
This chapter goes through a simple example experiment so you can see the basic steps involved in processing the data from a single participant. The experiment is from the
ERP CORE
(Kappenman et al., 2021), and it is designed to isolate the N400 component that is elicited when a word is semantically unrelated to a previous word (e.g., SHOE when it’s preceded by TREE instead of by SOCK).
We’ll go through the most basic EEG processing steps (e.g., epoching, baseline correction, artifact detection) and create averaged ERPs for a single participant. In the next chapter, we’ll process additional participants, measure the N400 amplitude, and do a simple statistical analysis. The details of these steps will be described in later chapters, along with important details about how Matlab, EEGLAB, and ERPLAB work. These two chapters are designed for you to get the big picture of how the data are processed and learn the basics of using EEGLAB and ERPLAB. You can also find an overview of an entire EEG processing pipeline in
Appendix 3
.
If you’re already experienced with ERPLAB, you can just skim through this chapter. But if you don’t have much ERPLAB experience, you’ll want to download the data and do each data processing exercise. Remember, you’ll probably run into some error messages or other technical snags, but don’t get discouraged. An important implicit goal of this book is for you to learn how to troubleshoot technical problems. See the troubleshooting tips in
Appendix 2
if you have problems.