3: Processing Multiple Participants in the ERP CORE N400 Experiment

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Learning Objectives

In this chapter, you will learn to:

Run a script for making averaged ERPs for multiple participants
Create a grand average (an average of the single-participant averages)
Visualize the grand average waveforms and noise metrics
Apply low-pass filters to the grand average to minimize high-frequency noise
Quantify N400 amplitude from single-participant averaged ERP waveforms
Conduct a simple statistical analysis on the N400 amplitudes
Conduct a more complex statistical analysis
Run a script that automates the steps in this chapter

In the previous chapter, we processed the data from a single participant in the ERP CORE N400 experiment, up to the stage of creating and viewing the averaged ERP waveforms. In this chapter, we’ll process nine more participants and do the steps necessary to get to the stage of quantifying N400 amplitude and conducting a simple statistical analysis.

Between the previous chapter and the current chapter, you’ll be able to see most of the major steps required to go from raw data to a final conclusion. The details will be spelled out in subsequent chapters, and our goal here is for you to see the big picture. Also, to make things go quickly, we’ll be looking at only 10 of the 40 participants in the actual study. If you’re already experienced with ERPLAB, you can just skim this chapter.

Don’t forget to consult the troubleshooting tips in Appendix 2 if you run into error messages or other problems.