Masters Thesis

Changes in Visual Attention with Normal Aging.

There are unsettled debates in the literature regarding the strength of top-down and bottom-up processing in visual attention. Control of top-down visual attention was assessed in both younger and older adults using a visual search task. In the task, participants were first given the name of the target stimulus's color, then shown a series of eight circles arranged concentrically, each containing either a horizontal or vertical line. Two of the eight circles were color singletons; one was the target singleton and the other a distractor singleton. The rest of the circles were gray. The current study implemented the Stroop effect to manipulate the task difficulty by changing the font color of the cue word. Assessing the strength of top-down attentional control was achieved by determining whether response time (RT) was dependent on the cue type and congruency of the target and distractor line orientations. It was hypothesized that older adults would demonstrate a weaker top-down control of visual attention than younger adults in the visual search task. However, a mixed-effect model analysis revealed that the younger adults showed the expected Stroop effect when comparing cue types, whereas older adults showed only a partial effect. Moreover, the congruency effect manifested only in younger adults. Given the unexpected results, future research should look at neurological differences between older and younger adults while performing tasks that manipulate top-down control of visual attention to better understand the effect of aging on attentional control.

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