The relation between lateral shifts of visual attention and saccade preparation was investigated, by measuring EEG differences contra-ipsilateral to the relevant stimulus or to the required saccade.

In experiment 1, participants had to make saccades either to a saliently coloured or to a grey circle, simultaneously presented in opposite visual hemifields, under different task instructions. Three components of lateralisation were found:

1. an inferior-parietal component, 250 ms after stimulus onset, reflecting the shifting of attention to the relevant stimulus.
2. another inferior-parietal but more wide-spread component, at 400 ms, reflecting the enhancement of the attentional shift if the relevant stimulus was also the saccade-target.
3. activity contra-lateral to saccade direction, beginning about 100 ms before the saccade, largest above mesial parietal sites, with some task-dependent fronto-central contribution, reflecting saccade-associated activity.

In experiment 2, preparatory activity was measured in the S1-S2 interval in a choice-response task with four alternatives (look or press right or left), following different amounts of S1 information. When providing information about movement side, S1 evoked contra-lateral parietal activity at 300 ms and fronto-central activity at 400 ms, with the fronto-central component being larger and the parietal component being smaller when saccades were announced than when key-presses were announced. These two components might be related to component (1) and (2) of experiment 1, again reflecting saccade-related shifts of attention in the parietal and frontal systems.