Figure 1.

Experimental paradigm, readiness potential activity, and temporal dynamic of visual accuracy. A, Schematic timeline of an example trial in the visuomotor task. Participants pressed a key to start the trial. The visual stimulus comprised two gratings with different spatial frequency, displayed after a random delay on the left or right hemifield. Participants had to indicate which grating (upper or lower) had the higher spatial frequency by means of a verbal response. B, Time course of readiness potential relative to the button press. The light blue and orange lines show the grand-averaged ERPs in the visuomotor and motor-only tasks, respectively, relative to action onset (0 s). Colored shaded areas indicate the standard error. The ERPs reflect the average activity at eight electrodes of interest: FC1, C3, CZ, CP5, CP1, CP2, P3, highlighted in blue in the inset. The intensity map of the topographical EEG plot shows the ERP slope in the interval −0.5 to −0.02 s from the keypress for all electrodes. C, Temporal dynamic of visual accuracy as a function of visuomotor delays, for the aggregate observer (n = 18). Triangles and circles mark accuracies for short and long ASIs, respectively. Gray thick line shows the best asymptotic exponential fit to the data. D, Perceptual accuracy for stimuli presented after short ASIs (delays < 120 ms, x-axis in dark yellow) and long ASIs (delays > 600 ms, y-axis in green). The open circles represent the individual accuracies (n = 18); the black dashed line is the equality line. The red cross shows the group mean accuracy ± 1 SEM. Modulation of visual perception was estimated as the difference between the individual long and short ASIs accuracy. See Extended Data Figure 1-1 for readiness potential activity when using an earlier baseline (−0.5 to −0.4 s), Extended Data Figures 1-2 and 1-3 for eye movements analyses, and Extended Data Figure 1-4 for the topography of the slope of the ERPs in the motor-only condition.