Appendix 2:

Overview of all dual-tasking experiments included in the analysis

Publication	No. of subjects	Contrast	Stimulus modality	Effector modality	S–R modality compatibility	Task order
Deprez et al. (2013)	33	Dual task > single tasks	Vis aud	Man man	Incompatible	Fixed
Dreher and Grafman (2003)	8	Dual task > baseline	Vis vis	Man man	Compatible	Random
Erickson et al. (2005)	33	Dual task > single tasks	Vis vis	Man man	Compatible	Random
Hartley et al. (2011)a	12	Short SOA > long SOA	Vis vis	Man man	Compatible	Fixed
Hartley et al. (2011)b	12	Short SOA > long SOA	Vis vis	Man man	Compatible	Fixed
Herath et al. (2001)	10	Dual task > single tasks	Vis som	Man man	Incompatible	Random
Herath et al. (2001)	10	Short SOA > long SOA	Vis som	Man man	Incompatible	Random
Hesselmann et al. (2011)	12	Dual task > single tasks	Vis vis	Man man	Compatible	Fixed
Houtkamp and Braun (2010)	12	Dual task > single tasks	Vis vis	Man man	Compatible	Random
Jiang (2004)	10	Short SOA > long SOA	Vis vis	Man man	Compatible	Fixed
Jiang et al. (2004)	26	Short SOA > long SOA	Vis vis	Man man	Compatible	Fixed
Koechlin et al. (1999)	6	Dual task > single tasks	Vis vis	Man man	Compatible	Random
Mochizuki et al. (2007)	15	Dual task > single tasks	Vis aud	Man man	Incompatible	Fixed
Mochizuki et al. (2007)	15	Dual task > single tasks	Vis aud	Man voc	Compatible	Fixed
Schubert and Szameitat (2003)	11	Dual task > single tasks	Vis aud	Man man	Incompatible	Fixed
Sigman and Dehaene (2008)	21	Dual task > single tasks	Vis aud	Man man	Incompatible	Fixed
Stelzel et al. (2006)	10	Dual task > single tasks	Vis aud	Man voc	Incompatible	Fixed
Stelzel et al. (2008)c	13	Dual task > baseline	Vis aud	Man man	Incompatible	Fixed
Stelzel et al. (2008)d	13	Dual task > baseline	Vis aud	Man man	Incompatible	Fixed
Stelzel et al. (2008)e	13	Dual task > baseline	Vis aud	Man man	Incompatible	Random
Stelzel et al. (2008)f	13	Dual task > baseline	Vis aud	Man man	Incompatible	Random
Szameitat et al. (2002)	11	Dual task > single tasks	Vis aud	Man man	Incompatible	Fixed
Szameitat et al. (2002)	11	Dual task > single tasks	Vis aud	Man man	Incompatible	Random
Tombu et al. (2011)	12	Dual task > single tasks	Vis aud	Man voc	Compatible	Random
Vetter et al. (2011)g	18	Dual task > single tasks	Vis vis	Man man	Compatible	Fixed
Vetter et al. (2011)h	18	Dual task > single tasks	Vis vis	Man man	Compatible	Fixed

vis visual, man manual, aud auditory

^aYounger participants

^bolder participants

^cSet-4

^dSet-8

^eSet-4

^fSet-8

^ghigh load > single task

^hlow load > single task