Uninformative symbolic cues may bias visual-spatial attention: Behavioral and electrophysiological evidence

Event-related brain potentials and response latencies were measured in an experiment where centrally presented arrow cues were followed by left or right visual target stimuli. In one condition, target location was indicated by the cues with 75% validity. In another condition, the precues were uninformative with respect to target location. Faster response times and larger negativities in the ERPs at midline electrodes were measured for targets at cued locations following informative cues, but also with uninformative precues. This indicates that visual-spatial attention may be biased involuntarily by central symbolic precues. (C) 1997 Elsevier Science B.V.