M. E. LAVOIE, J. E. A. STAUDER
154
Figure 4. Stimulus-locked LRP scalp distribution from lat-
eralized locations showing the correct maximum activation
(with standard error of the mean) to blocked and mixed de-
signs (averaged across compatible-incompatible conditions).
The figure show a design by electrode interaction found on
the LRP peak amplitude. The LRP amplitude w as larger in
the blocked than in the mixed design at FC3’, C3’and CP3’
respectively.
stimulus location a fast direct route is activated, whereas
a slower indirect (controlled) route activates the inten-
tionally selected response [23]. However, the discrepancy
in the compatibility effect between RT and LRP onset
measures in the mixed design could be attributed to the
larger LRP-RT difference to the mixed (271 ms) as com-
pared to the blocked design (176 ms). Thus, in the con-
text of a mixed design, LRP onset is more distant from
the RT and produces a delayed speed of response activa-
tion as compared to the blocked design because of a de-
layed translation time to decode the response program.
In conclusion, our data showed a slower LRP onset
and reaction times to the incompatible mapping, greater
in the mixed design and favor a serial processing expla-
nation of the stimulus-response conflict. Moreover, the
LRP amplitude activation during the mixed design con-
sistently showed smaller amplitude at fronto-central ar-
eas (design by electrode interaction), revealing that more
selective inhibition was necessary to perform the condi-
tional mixed task.
5. Acknowledgements
This work was supported by a Fonds pour la Recherche
en Santé du Québec (FRSQ) clinical research (5271) and
the FRSQ chercheur-boursier awarded to MEL. At last
but not the least, we thank all participants for their pre-
cious contribution in this study.
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