When compensation fails: attentional deficits in healthy ageing caused by visual distraction.

Age related changes in frontal lobe functions are often related to attentional deficits that lead to increased distractibility by irrelevant stimuli. However, attentional functions have been reported not to decline in general with increasing age but simply be too slow to deal properly with distraction in time. Therefore older people might be able to compensate for distraction quite efficiently with sufficient processing time. Compensation, however, might fail when early perceptual processing is affected by distraction already. In the present study, a change in luminance or in orientation had to be detected in a sequence of two visual frames. Older participants showed reduced performance only when luminance and orientation changes were presented simultaneously at separate locations (perceptual conflict condition). Sensory ERP components were not overall altered with increasing age. Only in conflicting trials, a strong bias towards physically more salient information was observed. Additionally, older adults showed markedly delayed ERP-correlates of fronto-central control mechanisms in the conflict condition. The data indicate that processing deceleration cannot compensate for perceptual conflicts induced by mis-weighting of incoming information.