OVERT ORIENTING IN THE RAT - PARAMETRIC STUDIES OF CUED DETECTION OF VISUAL TARGETS

Covert shifts of visual attention in space have been quantified by mea suring the effects of visual cues on the detection of visual targets i n humans and monkeys maintaining visual fixation. These observations o f ''covert orienting'' have provided important information regarding t he neurobiology of visual attention in primates. This article describe s a cued spatial target detection task for physically unrestrained rat s. Valid cues (spatially contiguous with the target) enhanced target d etection, and invalid cues (spatially discontiguous with the target) d egraded target detection. Both visual and auditory cues were effective . These validity effects could not be explained by stimulus additivity or response preparation mechanisms, whereas a cue-independent ''alert ing effect'' appeared to reflect response preparation. The effects com pare favorably with primate work and suggest that this method may enab le assessment of visual attention shifts in rats.