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Rhythmic Coordination
Single Limb
Some of my research has investigated the coordination of rhythmic movements of a single limb (e.g., arm in hammering). This research has demonstrated that the timing and spacing of these movements can be explained if one assumes that the nervous system has assembled a nonlinear oscillator system at the joint being controlled (Turvey, Schmidt, Rosenblum, & Kugler, 1988; Turvey, Schmidt, & Rosenblum, 1989; Kugler, Turvey, Schmidt, & Rosenblum, 1990; Schmidt, & Turvey, 1992; Kadar, Schmidt, & Turvey, 1993; Beek, Turvey, & Schmidt, 1992; Beek, Schmidt, Morris, Sim, & Turvey, 1995). In brief, single limb rhythmic movements seem to be governed by the same principles as the pendulum on a clock!
Interlimb
Some of my research has investigated the coordination of rhythmic movements of a single limb (e.g., arm in hammering) and the interlimb coordination of rhythmic movements at two limbs (e.g., the legs in walking or running). The research on the coordination of rhythmic movements of two limbs has suggested that the relative timing or relative phasing of two limbs can best be explained by assuming that the cognitive processes assemble a nonlinear oscillator system for each limb and that these systems interact (i.e., are coupled) across the nervous system (Turvey, Rosenblum, Schmidt, & Kugler, 1986; Bingham, Schmidt, Turvey, & Rosenblum, 1991; Schmidt, Beek, Treffner, & Turvey, 1991; Schmidt, Treffner, Shaw, & Turvey, 1992; Sternad, Turvey, & Schmidt, 1992; Schmidt, Shaw, & Turvey, 1993; Schmidt & Turvey, 1995). The heart of this research has been showing that the coordination patterns observed in interlimb coordination are just those predicted by a mathematical model of a coupled oscillator system (e.g., the Haken-Kelso-Bunz equation). In short, coordinated limbs act like two interacting pendulum clocks on a wall. If these clocks are initially unsynchronized, their mutual interaction by vibrations in the walls cause them to become synchronized. In sum, this research has shown that cognitive systems appropriate the organizational strategies of coupled oscillators—an organizational strategy of inanimate nature—to create coordinated rhythmic acts.
Clapping
Collaboration with Paula Fitzpatrick at Assumption College has extended the coupled oscillator theory to a natural interlimb coordination task, namely, clapping (Fitzpatrick, Schmidt & Carello, 1996). This research demonstrates that dynamical processes of self-organization not only occur in laboratory interlimb coordination tasks but in very natural movements as well. Having defined a naturalistic task to test the dynamical hypotheses on interlimb coordination allowed us to investigate how the dynamical strategies are acquired in development. In a study that we began at Tulane University and finished at Holy Cross, using 3, 4, 5, and 7 year olds, we developed methods for measuring the strength of the regime used to coordinate the arms in clapping and found that younger children have weaker coordination regimes and that an adult pattern of clapping is developed by the seventh year (Fitzpatrick, Schmidt, & Lockman, 1996).
Breathing and Sucking in Preterm Infants
Collaboration with Eugene Goldfield and Peter Wolff of Harvard Medical School led to model the coordination involved in breathing and sucking of infants and determine whether dynamical indices of coordination (those used in my studies of adult interlimb coordination) distinguish full-term, healthy pre-term and high-risk preterm infants (Goldfield, Schmidt, & Fitzpatrick, 1999; Goldfield, Wolff, & Schmidt, 1999a; Goldfield, Wolff, & Schmidt, 1999b). In brief, coordination patterns of breathing rhythms (coupling of chest and abdomen in respiration) and the coordination of breathing and sucking rhythms indicate the presence of a dynamical coupled oscillatory control structure. Further, indices of the strength of this dynamic differentiate these infant groups. |
