Pm. Greenwood et al., CONTROLLING THE FOCUS OF SPATIAL ATTENTION DURING VISUAL-SEARCH - EFFECTS OF ADVANCED AGING AND ALZHEIMER-DISEASE, Neuropsychology, 11(1), 1997, pp. 3-12
It was hypothesized that slowed visual search in healthy adult aging a
rises from reduced ability to adjust the size of the attentional focus
. A novel, cued-visual search task manipulated the scale of spatial at
tention in a complex field in healthy elderly individuals and patients
with dementia of the Alzheimer type (DAT). Precues indicated with var
ying validity the size and location of the area to be searched. Locati
on precues exerted the strongest effects on conjunction search and the
weakest effects on feature search. As the size of valid location cues
decreased, conjunction search was facilitated. These effects declined
progressively with advanced age and the onset of DAT. As the size of
invalid cues increased, conjunction search was first facilitated, then
slowed, but neither age nor DAT altered this effect. These results in
dicate that both Alzheimer's disease and, to a lesser degree, advanced
aging, reduce control of the spatial focus of attention.