Appropriate Correction for Multiple Comparisons in Decoding of ERP Data: A Re-Analysis of Bae & Luck (2018)

Bae & Luck (2018) reported a study of visual working memory in which the orientation being held in memory was decoded from the scalp distribution of sustained ERP activity and alpha-band EEG oscillations. Decoding accuracy was compared to chance at each point during the delay interval, and a correction for multiple comparisons was applied to find clusters of consecutive above-chance time points that were stronger than would be expected by chance. However, the correction used in that study did not account for the autocorrelation of the noise and may have been overly liberal. Here, we describe a more appropriate correction procedure and apply it to the data from Bae & Luck (2018). We find that the major clusters of time points that were significantly above chance with the original correction procedure remained above chance with the updated correction procedure. However, some minor clusters that were significant with the original procedure were no longer significant with the updated procedure. We recommend that future studies use the updated correction procedure.