## Doctoral Dissertations

#### Title

Learning a bimanual rhythmic coordination: Schemas as dynamics

January 1996

#### Keywords

Psychology, Behavioral|Psychology, Experimental|Psychology, Cognitive

Ph.D.

#### Abstract

Generativity--the ability of an individual to produce a skill under novel circumstances--is a persistent problem in motor learning addressed traditionally in the context of motor schema theory (R. A. Schmidt, 1976). The acquisition of an effective motor schema requires practice condition variability and knowledge of results (KR; e.g., Heuer & R. A. Schmidt, 1988; Kernodle & Carlton, 1992). The hand-held pendulums paradigm of Kugler and Turvey (1987) was used in five experiments to study the acquisition of a bimanual rhythmic coordination with relative phasing of either $-\pi/2$ or $-\pi/4$. In Experiment 1, participants acquired $-\pi/2$ under limited practice conditions and without KR. Despite these limitations, they demonstrated generativity in Experiment 2. Evidence was found for the effector-independence of the motor schema. The suggestion was made that the content of the motor schema is a coordination dynamic, whose acquisition is reliant on neither practice condition variability nor KR. In Experiment 3, the acquisition of two different motor schemas (one each for $-\pi/2$ and $-\pi/4$) was found to be identical at the level of the coordination but nonidentical in terms of the degrees of freedom recruited to produce the movements of the individual hands. Dimensionality analysis--meaningful only in the context of the schema as dynamics--revealed that the pattern dynamic at the level of the hands for both $-\pi/2$ and $-\pi/4$ was a strange attractor (chaotic in nature), rather than the commonly assumed "noisy" limit cycle (Kay, 1988). Evidence was found in support of the power law of learning (Fitts, 1964). In Experiment 4, generativity was demonstrated for both $-\pi/2$ and $-\pi/4$, with the coordination dynamics of $-\pi/4$ displaced uniformly in the direction of $-\pi/2$. In Experiment 5, acquisition of $-\pi/2$ and $-\pi/4$ was found to have caused an overall deformation in the attractor landscape of intrinsically stable patterns of in-phase and anti-phase. Together with the evidence that learning is of a coordination dynamic and that learning influences a coordination dynamic, evidence of chaos at subsystem levels indicates that generativity in learning comes from the chaotic nature of the coordination dynamic. ^

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