ERPLAB Toolbox is a freely available, open source set of MATLAB routines for analyzing event-related potential (ERP) data. It uses the freely available, open source EEGLAB toolbox as a front end. That is, EEGLAB is used to read in EEG data files and perform various operations on the EEG, and ERPLAB contains a set of new functions, which are added as plug-ins into EEGLAB, extending the set of operations that a user can perform within EEGLAB. These plug-ins include additional EEG processing manipulations (e.g., new functions for marking trials with artifacts) along with functions that provide powerful methods for sorting EEG epochs and averaging them together. Once a set of averages has been created, they are saved in binary files and can be exported into text files (allowing them to be imported into other ERP analysis systems).

ERPLAB also contains a set of routines that operate on the averaged ERP waveforms (e.g., making difference waves, plotting, filtering, measurement, etc.). We are still in the early stages of implementing these routines, but most of the basics are available.

As in EEGLAB, the ERPLAB routines can be accessed from the Matlab command window and from Matlab scripts in addition to being accessed from the EEGLAB GUI. Consequently, ERPLAB provides the ease of learning of a GUI-based system but also provides the power and flexibility of a scripted system.

The ERPLAB routines were inspired by ERPSS (the Event-Related Potential Software System), which was developed in Steve HillyardÕs lab at UCSD under the direction of Jon Hansen. However, the code is entirely new, and it is not designed to be fully backward compatible with ERPSS. Anyone who knows how to use ERPSS will be able to learn ERPLAB rapidly. But those who do not know ERPSS will also find ERPLAB approachable because of the GUI.