Brockton/West Roxbury, and Boston

Processing of unattended semantic information was examined in 13 patients with Alzheimer's disease (AD) and 23 normal controls (NC) using a selective attention, priming task. Two vertically aligned pictures of objects served as primes, and object names were targets. Participants were instructed to attend to only 1 picture, defined by color, in the prime display. NC participants showed facilitation only for target items that were the name of the attended prime picture, but AD patients showed facilitation from the attended and unattended prime pictures. Two accounts of these data posit a deficit in the initiation of the selection component of selective attentional processing in AD. On the basis of spotlight theories, a 3rd account posits a deficit in AD patients' ability to adjust the scope of the selection "beam. " Last, facilitation of attended and unattended information may be due to crosstalk between accurately selected and unselected information. Implications of the activation of irrelevant information to language function in AD are also discussed. There is emerging consensus that the language deficits in patients with Alzheimer's disease (AD) reflect a disruption in the semantic memory system. These deficits are revealed by poor verbal fluency (e.g., Chcrtkow & Bub, 1990; Hodges