Age-related differences in global-local processing: stability of laterality differences but disproportionate impairment in global processing.

Visual processing of global and local features differentially engages the right and left hemispheres and requires different allocations of spatial attention. To further understand the decline in visual cognition and visual attention with age, we studied the performance of healthy young subjects and healthy elders on a global-local figures task. The results showed that elders processed global images more quickly when presented in the left visual field and local images in the right visual field, similarly to the young controls. However, we did observe a significant impairment in the elders' ability to process global figures compared with local figures, despite there being no overall difference between global and local processing speed among the young. It is thought that this age-related decline in global processing is related to the narrowed attentional field that can be demonstrated in other age-related visual processing declines such as visual search and useful field of view.