“…With the simple paradigm of two people moving their fingers back and forth in view of one another, we are able to obtain continuous state variables describing the trajectory of each participant's effector at the behavioral level, their coordination dynamics (viz. the relative phase between the two finger movements, see "Order parameter" below; Tognoli et al, 2007;Oullier et al, 2008;Tognoli, 2008; see also Schmidt et al, 1990Schmidt et al, , 2011Richardson et al, 2007;Schmidt and Richardson, 2008;Marsh et al, 2009;Janata et al, 2012;Reddish et al, 2013;Fine and Amazeen, 2014;Fusaroli et al, 2014;Keller et al, 2014;Tschacher et al, 2014;de Poel, 2016;Moreau et al, 2016; for a variety of related approaches). Further, when expanding this work, information can be gained about concomitant activities in the brain (Tognoli et al, 2007;Jantzen et al, 2008;Naeem et al, 2012; see also Hari and Kujala, 2009;Dumas et al, 2011;Sänger et al, 2011;Konvalinka and Roepstorff, 2012;Pfeiffer et al, 2013;Babiloni and Astolfi, 2014;Cacioppo et al, 2014;Hirata et al, 2014;D'Ausilio et al, 2015;Koike et al, 2015;Zhou et al, 2016;Kawasaki et al, 2018;Mu et al, 2018;Pezzulo et al, 2019), and in emotional subsystems (e.g., Zhang et al, 2016; see also Anders et al, 2011;Balconi and Vanutelli, 2017;…”