Feature processing during visual search in normal aging: Electrophysiological evidence

Abstract

Event-related potentials (ERPs) were recorded from healthy young and older subjects during the execution of a visual search task in which they were required to detect the presence of a target stimulus that differed from distractors in a salient feature (orientation). Apart from the orientation target, a task-irrelevant singleton defined by a different feature (color) was also presented without instruction. The effects of normal aging on the N2pc component, an electrophysiological correlate of the allocation of visuospatial attention, were evaluated for the first time. Behavioral results showed an increase in the mean reaction time (RT) and a reduction in the hit rates with age. Electrophysiological results showed a consistent N2pc for orientation target pop-outs but not for irrelevant color pop-outs in both age groups, suggesting that the irrelevant color singleton did not induce attentional capture. Furthermore, the N2pc component observed for orientation targets was significantly delayed and attenuated in older subjects compared to young subjects, suggesting a specific impairment of the allocation of visuospatial attention with advancing age.

Influence of age and gender in motor performance in healthy subjects

“…In contrast with other motor tasks, the mean values of VRT did not differ significantly between both genders. Previous reports with different tests on simple or complex reaction time tasks, showed response times longer in elderly people [21][22][23][24][25][26][27].…”

“…Male subjects were faster than females in the PS task [14], while the range of forearm rotation was higher in women than in men in single studies [20]. Aging seems to influence the performance of simple or complex reaction time tasks, including visual reaction time (VRT), being the response times longer in elderly people [21][22][23][24][25][26][27].…”

Perceptual load, voluntary attention, and aging: An event-related potential study

“…These effects point to differences in the magnitude of early visual processing between the young and old groups. The N1 latency was later in the old than in the young group, indicating that the older participants need more time to localized the target in the visual search array than young participants (Lorenzo-López et al, 2008). But the P1 latency was earlier in the old than in the young group.…”

“…Other ERP studies (Bashore, 1990; Strayer et al, 1987) have shown that the effects of aging mainly occurred at the stimulus encoding and response-related stages of information processing. In a visual search task, Lorenzo-López et al (2008) found that the latency of N2pc component was smaller and approximately 68 ms later in old than in young group. As the N2pc amplitude was considered as index of attention focusing, they suggested a reduction in attentional processing resources for old adults.…”

Normative shifts of cortical mechanisms of encoding contribute to adult age differences in visual–spatial working memory

“…In contrast to the maintenance stage, thus far these aspects of visual-spatial WM encoding and aging have not been investigated. We expected older adults to show a deficit in their attentional focus, which would be reflected in an attenuation of the N2pc component, relative to younger adults (Li et al, 2012;Lorenzo-Lopez et al, 2008). Furthermore, older adults would possibly engage another encoding mechanism to attenuate the adverse consequences of this deficit on WM performance.…”