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Abstract:
Abstract: Aging exerts non-linear effects on attentional
scaling in visual search, such that the facilitation of RT
following small precues is heightened in "young old" elderly
compared to young adults but is diminished in "old old" elderly
(Greenwood & Parasuraman, 1999). Eriksen & St. James (1986)
argued that the processing benefit within the attentional focus is
reduced as the cued region is enlarged. Based on our work with RT
measures, such a view would predict both: (a) linear increase in
accuracy of target detection with decreased cue size; (b)
enhancement of that increase in the young old. To test these
predictions, young and young old performed speeded search in which
precues predicted target location with variable precision in a 25
letter array (150 msec duration). Precue size (1, 4, 9, 16, 25
letters enclosed) and cue-target SOA (200, 500, 700 msec) were
varied. Accuracy was highest when the precue enclosed four letters
(p<.05). Contrary to predictions from RT measures with long
duration displays in which conjunction search was speeded following
a precise precue, with brief duration displays search accuracy was
reduced when the precue was precise but increased when the precue
enclosed several array elements. Results indicate deployment of
visuospatial attention changes with display duration so that when
displays are brief a broad attentional focus facilitates
conjunction search both in young and old.
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