The time course of spatial orienting elicited by central and peripheral cues: evidence from event-related brain potentials

To study differences in the time course of attentional orienting triggered by salient peripheral events and by central symbolic precues, event-related brain potentials (ERPs) were recorded in response to letter stimuli follow ing spatially informative symbolic or peripheral precues after a cue-target interval (CTI) of either 200 or 700 ms. Stimuli at cued (attended) locatio ns elicited an enhanced negativity relative to stimuli at uncued locations. With short CTIs. these effects started around 150 ms post-stimulus for per ipheral cues. They were delayed by about 100 ms for central cues. This late ncy difference is assumed to reflect fast exogenous orienting elicited by p eripheral, but not by central cues. Beyond 200 ms post-stimulus, attentiona l negativities were larger with long CTIs than with short CTIs for both cue types, presumably related to the gradual build-up of endogenous orienting triggered by spatially predictive events. (C) 2000 Elsevier Science B.V. Al l rights reserved.