Figure 2. Longer readiness period causes higher fMRI signal in the absence of motor output.

(A) The gray circle may be filled with red or green with equal probability. Participants are instructed not to press the button when they see red. (B) The post-trial fMRI signal amplitude is correlated with the readiness period in both the go (green) and no-go (red) trials (p-values of the correlation, inset). Note that baseline activity is slightly lower in the no-go condition, suggesting that motor output provides a constant signal offset that is independent of the waiting-time-dependent encoding described in this paper. For comparison, the dashed line shows the signal from the original experiment (Figure 1D). Error bars SEM.