Adult age differences in the time course of inhibition of return

Inhibition of return (IOR) occurs when people are slower to detect a target that appeared at a previously cued location. Prior research has shown that younger and older adults display similar amounts of IOR, but this research has not examined the time course of the process. Because elderly people may be slower to engage or disengage spatially based attention, the present experiment examined age differences in IOR at stimulus-onset asynchronies ranging from 50 ms to 3,000 ms. The results show that the peak magnitude of IOR was similar for younger and older adults, but the onset of IOR occurred approximately 300 ms later in elderly persons. Older adults also showed a greater degree of facilitation at shorter stimulus-onset asynchronies. The results suggest that there is a change in the temporal dynamics of inhibition that occurs with age. T HE ability to efficiently direct visual attention to salientfeatures in the environment is a critical function of the visual system. Efficiency involves enhancing detection of stimuli at locations that are currently attended and directing attention away from locations that were recently attended. The observation that people are slower to detect a target that appeared at a recently cued location has been referred to as inhibition of return (IOR; Posner & Cohen, 1984; Posner