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Abstract:
The importance of motivational signals in guiding attention
and action is widely recognized in research on animal behavior, but
has been little investigated in cognitive research on skilled
performance in humans. Using a task switching paradigm and
incentive manipulations, Poulsen and Segalowitz (2000) demonstrated
that motivational experience can exert a considerable and selective
influence on executive control of set switching as assessed by
reaction time measures. The present study applied dense-array
(128-channel) ERP methods to differentiate effects of motivation on
endogenous preparatory (prestimulus) and exogenous implementation
(poststimulus) phases of task-set switching. Using a left/right
button press, participants earned points for fast and accurate
letter (vowel/consonant) and digit (even/odd) target judgments,
while ignoring a competing (letter or digit) or neutral (symbol)
foil (e.g., A3, *G). After task-blocked training, participants
responded to pseudo-randomly mixed blocks of cued letter and digit
trials. Participants received equal (4-point) or differential (6-
versus 2- point) incentives for letter and digit trial performance
during training, followed by equal incentives during the switch
task. Motivational modulation of the CNV preceding switch versus
repeat trials, and of the poststimulus late positive complex is
examined. Also contrasted is the ERN following feedback on
previously high- versus low-incentive task trials. Implications
regarding candidate brain mechanisms mediating these effects are
discussed.
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