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Abstract:
Dynamic Field Theory (DFT) (Schoner, Kopecz, & Erlhagen,
1997) proposes that information content is as important as the
quantity of information for motor planning. For example, in a
pointing task, DFT hypothesizes reaction time is influenced by
target spacing as well as by the number of targets. DFT predictions
were examined for a two choice, variable target spacing experiment
consisting of a pointing task and a reacting task. Reaction time
(RT) and evoked potentials (EP) were recorded. In each of two
conditions, a frequent arrow (80%) or a rare arrow (20%) was
presented briefly to specify movement direction from a central
position. In the narrow condition, the frequent arrow appeared
20deg. clockwise/counter-clockwise from the rare arrow. In the wide
condition, the frequent arrow appeared 120deg.
clockwise/counter-clockwise from the rare arrow. In both
conditions, the rare arrow specified the same movement direction.
RT data (n=10) indicated a frequency by condition by task
interaction that was predicted by DFT. Particularly interesting,
movement onset to the identical rare arrow was faster in the narrow
than in the wide condition for the pointing task. Preliminary ERP
data (n=10) indicated a change in power after stimulus appearance
based upon the directional metrics of the individual conditions.
Both the RT and the EP results were consistent with predictions of
DFT. Supported by NSF grant SBR-9709361.
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