Adult age differences in phasic alerting effects on components of visual attention

[摘要] Visual attention is a multi-component function that underlies effective behavior in our visual environment. Thus, age-related changes in visual attention can cause difficulties in many every-day tasks. Alertness, the system's state of general readiness to react to sensory stimuli, is closely linked to the efficiency of visual attention. However, which components of attention are affected by alertness, and how this changes with aging, is unclear. In the present study, we investigated effects of phasic alerting on distinct parameters of visual attention based on the computational Theory of Visual Attention (TVA). In groups of younger and older adults, we modeled parameters in a partial report task, in which half of the displays were preceded by an auditory warning cue. We further measured visual event-related lateralizations (ERL) to derive neurophysiological correlates of the alertness and age effects on visual processing stages. Younger adults showed an alertness-related processing facilitation: Parameter sensory effectiveness a, a measure of visual processing capacity, was significantly increased. The behavioral effect was accompanied by a latency reduction of the ERLs following the warning cue, indicating speeded resource allocation to visual processing areas. By contrast, older adults did not benefit from the alerting cue: Parameter sensory effectiveness a, and ERL latencies, were not modulated by the cue. The relative distribution of processing capacity according to spatial locations and task-relevance, reflected in parameters spatial bias windex and top-down control a, respectively, were unaffected by phasic alerting in both age-groups. The findings are in accordance with a recent extension of TVA, claiming that phasic alertness increases the overall processing capacity by multiplying all neural activations representing visual categorizations with a common factor. They further indicate age-related changes in the brain network underlying alertness and attention, which governs the responsiveness to external cues and is crucial for general cognitive functioning in aging.

[学科分类] 眼科学