A Comparison Of Attentional Processing In Younger And Older Observers
Carolyn J. Harp, Ronald A. Rensink, Cambridge Basic Research, Cambridge, Massachusetts, USA.

Investigative Ophthalmology & Visual Science, 40:50. 1999. [ARVO 1999; Ft. Lauderdale, FL.]

Purpose. To assess how attentional processing changes with age. Two aspects of attention were examined: processing speed and filtering ability.

Methods. Experiments used the "flicker" paradigm to measure performance in younger and older observers. The search arrays consisted of black rectangles and white rectangles, each with 80-800 ms on-time and 120 ms off-time (blank). The target item was always a rectangle changing orientation. Three display types were used in the experiments: static black rectangles, static black and white rectangles, and dynamic black and white rectangles that continually changed contrast. A pop-out search display (searching for a horizontal bar among verticals) was used as an initial screening of attentional function.

Results. Reaction time (RT) slopes were the same for all observers in the pop-out display. For the change experiments, RT slopes for the older group were twice those of the younger group. The slopes in the static and dynamic displays were the same, however, indicating that basic perceptual processing speed was unaffected by variations in irrelevant properties. While the varying displays did not cause a baseline RT shift in the younger group, the older group did exhibit a rise in baseline RT, possibly reflecting a criterion shift.

Conclusions. While there is a general slow-down of attentional processing speed in the older group, there appears to be no interference with their ability to filter out irrelevant stimuli. Older observers may also tend to be more cautious in their decision process as the variation in the display increases.

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