Abstract
Normal aging of visual processing was investigated using localization and categorization of filtered pictures of real objects. Image filtering aimed at biasing processing toward magnocellular (low-pass), parvocellular (band-pass) or both (no filtering) pathways whereas the tasks served to dissociate between dorsal (localization) or ventral (categorization) pathways. Thirty young adults adults (m=22,6; α=1,2) and 23 old adults (m=60,1; α= 6,8) were asked to semantically categorize (animal vs. tools) or to localize (up vs. down) 120 stimuli that were presented onscreen for 200 ms in three different versions: a low-pass filtered (centered on 0 cpd, with SF up to 3.8 cpd), a band-pass filtered (centered 3.8 cpd, with SF from 1.9 cpd up to 7.7 cpd), and a control stimuli (non-filtered). The main results were the interactions between task, group and filter that were found on error and on RT (p=.07). Contrast analysis showed that, in the semantic categorization task, a decreased correct response rate and increased RT was observed for old adultsrelative to young adults, especially for the band-pass filtered objects. In the localization task, the age-related deficit was higher for band-pass filtered than for the others objects on RT, but was equivalent for band-pass filtered and for non filtered objects on error. Compared to young, older adults showed deteriorated performance specifically in the conditions that isolated band-pass information, whatever the pathways involved, either dorsal or ventral. Moreover, magnocellular and parvocellular interactions were found, when the task involved the dorsal pathway. Our results are consistent with those of Viggianno et al. (2005, Archives of gerontology and geriatrics) giving additional evidence for a parvocellular loss in early normal aging.