Fig. 1.

Illustration of a sequence of stimulation in the visual modality.

Subjects performed a word recognition task in a sequence where the word “gauche” (left) and the word “droite” (right) appeared either at the left or the right part of a computer screen viewed through a mirror inside the magnet. The subjects were required to press the left or the right button of a response pad as quickly as possible according to the meaning of the word (e.g. left button when the word “gauche” appeared). There were two types of trials: 45% congruent trials (e.g. the word “droite” (right) appeared at the right side of the screen) and 55% incongruent trials (e.g. the word “droite” (right) appeared at the left side of the screen). During fMRI acquisition, congruent and incongruent trials alternated and were separated by variable inter-stimulus-intervals (ISI). Visual stimulations lasted 1.5 s and the ISI duration was comprised between 2.8 and 3.8 s.