Högskolan i Skövde

There is a well-noticed methodological variation within frontal alpha asymmetry (FAA) research. The impact such methodological variation might have on the FAA measure is investigated in this present study. More specifically, this investigation is a non-confirmatory, descriptive, and exploratory analysis of how different references influence the interpretation of resting-state FAA results. Hence, the focus is not on a potential change in the size of an FAA result, but rather on whether a potential change might shift the sign of an FAA result from a positive to a negative or vice versa, which would enable a different interpretation of the results.The analysis was performed using the open-source LEMON raw EEG dataset of 215 healthy adult subjects. The online FCz reference, the average, and the current source density (CSD) were investigated as well as the time of re-referencing, thus resulting in a total of five different reference setups. The dataset was processed through an automated data processing pipeline and revealed that for a majority of the subjects included in this study, the FAA value shifted from a positive to a negative or vice versa at least one time between the five different reference approaches, which consequently enabled a completely different interpretation of the results.These results are not only of major concern for the utility of the FAA measure but also suggest that FAA research might suffer from a broken derivation chain.