Larger effect of aging on the perception of higher-order stimuli

Widespread deficits an known to accompany normal aging. Contrast thresholds of older and younger observers were measured for static and drifting grati ngs defined by luminance (first-order) or by contrast (second-order), and f or a temporally segmented second-order motion stimulus. Results showed that older individuals had a larger threshold elevation for the perception of s econd-order stimuli than for the perception of first-order stimuli. This su ggests a dissociation between the mechanisms underlying the perception of f irst and second-order stimuli, and demonstrates that aging may affect the m ore numerous processing steps required for the analysis of higher level sti muli. (C) 2000 Elsevier Science Ltd. All rights reserved.