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Abstract:
In the precuing paradigm the lateralized readiness potential
(LRP) can be used to assess response programming as a function of
precued movement parameters. Precueing hand, direction, or force,
Ulrich et al. (1998) observed an increased LRP above mere hand
information only for fully prespecified movements, indicating a
strong version of hierarchical response preparation. We examined
whether these findings would hold also when information about
response hand and finger is separated. In Experiment 1 precues
provided partial to full advance information about response hand,
finger (index vs. middle), or movement direction. Replicating the
findings of Ulrich et al., the LRP increased above the level of
hand information only when the movement was fully specified.
However, because the LRP amplitude for hand plus finger information
was intermediate between the full and the other partial precue
conditions, testing power was raised in Experiment 2 by omitting
the full precue condition and increasing the number of trials per
condition. This time finger in addition to hand information did
indeed significantly increase the LRP amplitude above the level of
mere hand information, whereas no such effect was seen for hand
plus direction precues. Therefore the strong version of
hierarchical response preparation does not hold true when
information about the response finger is added to hand information.
In this case motoric preparation appears to advance above hand
preparation despite other yet to be specified movement parameters.
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