In search for the most optimal EEG method: A practical evaluation of a water-based electrode EEG system

The study assessed a mobile electroencephalography system with water-based electrodes for its applicability in cognitive and behavioural neuroscience. It was compared to a standard gel-based wired system. Electroencephalography was recorded on two occasions (first with gel-based, then water-based system) as participants completed the flanker task. Technical and practical considerations for the application of the water-based system are reported based on participant and experimenter experiences. Empirical comparisons focused on electroencephalography data noise levels, frequency power across four bands (theta, alpha, low beta and high beta) and event-related components (P300 and ERN). The water-based system registered more noise compared to the gel-based system which resulted in increased loss of data during artefact rejection. Signal-to-noise ratio was significantly lower for the water-based system in the parietal channels which affected the observed parietal beta power. It also led to a shift in topography of the maximal P300 activity from parietal to frontal regions. The water-based system may be prone to slow drift noise which may affect the reliability and consistency of low-frequency band analyses. Practical considerations for the use of water-based electrode electroencephalography systems are provided.Raw Data Files: EasyCap Raw EEG data recorded with the EasyCap system are provided in the EEG folder. The data were recorded using BrainVision Analyzer. These files can be imported for analysis in e.g. in EEGLab or Fieldtrip. Eprime files with Flanker task responses have been deposited in the Eprime folder. There are two formats including .edat2 (Eprime specific) and .csv (accessible in Excel, R etc.).Raw Data Files: Demographics Participant demographics including gender and age are provided in the Demographics.xls file. The file presents the matching of participants by ID in EasyCap and Mobita. There are also recording notes provided which indicate whether there is anything that needs to be taken into consideration before starting the analysis of each participant