The role of parietal cortex in global/local processing of hierarchical stimuli: a transcranial magnetic stimulation...

We studied whether the posterior parietal cortex contributes both to focus attention on one level and to switch attention between global and local levels of compound letters across trials. After 1 Hz repeated transcranial magnetic stimulation was applied to the left, right posterior parietal cortex, and the precentral gyrus, participants identified global and local target letters. We found that repeated transcranial magnetic stimulation over the left posterior parietal cortex resulted in faster global than local responses but did not affect global-to-local interference and the level-repetition effect. The results suggest that the neural mechanism underlying focusing attention on one level of compound stimuli is distinct from that mediating switching attention between global and local levels across trials.