$$\rightleftharpoonup{xx}$$
$$\longleftharp{xx}$$,
$$\longrightharp{xx}$$,
A correction to the Acknowledgements section was made in: Uncovering Beat Deafness: Detecting Rhythm Disorders with Synchronized Finger Tapping and Perceptual Timing Tasks.
The Acknowledgements section has been updated from:
This research was supported by an International Reintegration Grant (n. 14847) from the European Commission to SDB and a grant from Polish Ministry for Science and Education to JS.
to:
This research was supported by an International Reintegration Grant (n. 14847) from the European Commission to SDB, and by a grant from Polish Narodowe Centrum Nauki (decision No. Dec-2011/01/N/HS6/04092) to JS.