Stimulus-locked lateralized readiness potentials as a function of the combination of modality cueing and response cueing. Valid modality cues and valid response cues (blue line), valid modality cues and invalid response cues (red line), invalid modality cues and valid response cues (green line), invalid modality cues and invalid response cues (yellow line). At t = 0 the target stimulus was presented. The baseline for this analysis consisted in the activity in the interval -748 to -648 ms before target presentation. The three grey fields mark the time intervals over which the cueing effects on the LRP were analyzed.