Low autocorrelation can be a sign of a poor quality channel or component. Often these are noisy, poor contact, or heavily contaminated with muscle noise. Low autocorrelation at a lag of 20ms is often associated with muscle noise.

ar_acf(data, ...)

# S3 method for eeg_ICA
ar_acf(data, ms = 20, plot = TRUE, verbose = TRUE, threshold = NULL, ...)

Arguments

data

eeg_ICA object

...

additional parameters

ms

Time lag to check ACF, in milliseconds. Defaults to 20 ms.

plot

Produce plot showing ACF and threshold for all EEG components.

verbose

Print informative messages. Defaults to TRUE.

threshold

Specify a threshold for low ACF. NULL estimates the threshold automatically.

Value

A character vector of component names that break the threshold.

Methods (by class)

  • eeg_ICA: Autocorrelation checker for eeg_ICA objects

References

Chaumon, M., Bishop, D.V., Busch, N.A. (2015). A practical guide to the selection of independent components of the electroencephalogram for artifact correction. J Neurosci Methods. Jul 30;250:47-63. doi: 10.1016/j.jneumeth.2015.02.025

Author

Matt Craddock matt@mattcraddock.com

Examples

demo_sobi <- run_ICA(demo_epochs, pca = 10)
#> Reducing data to 10 dimensions using PCA.
#> Running SOBI ICA.
#> Setting tolerance to 0.0011
ar_acf(demo_sobi)
#> Estimating autocorrelation at 20ms lag.
#> Estimated ACF threshold: -0.16
#> Subthreshold components:  

#> character(0)