Aging effects on semantic and phonological processing in picture naming.

摘要

This research tests two alternative accounts of older adults' deficits in word production, namely, transmission deficits at the phonological level or global inhibitory deficits. Semantic and phonological processes were investigated in young and older adults' naming using the picture word-interference paradigm. In Experiment 1, picture-naming latencies for objects with homophone names (e.g. ball) were compared for auditory distractors that were semantically similar to the depicted meaning (frisbee), semantically similar to the non-depicted meaning (dance), or were unrelated (hammer). Contrary to findings with young adults (Cutting & Ferreira, 1999), but consistent with the Transmission Deficit hypothesis, older adults showed no benefit from distractor words related to the non-depicted meaning, an effect dependent on top-down transmission of priming to the phonological level. Both young and older adults named more slowly with semantic distractors, but when age-related slowing was controlled, the magnitude of the effect was greater for older adults in only one of two conditions. Experiment 2 tested whether bottom-up processing was intact in old age, and whether the age difference in the semantic interference effect was an artifact of older adults' elaborated semantic network, or due to inhibitory deficits. Using the same paradigm as in Experiment 1, picture-naming latencies for objects (e.g. apple ) were compared for auditory distractors that were related to the picture name semantically (peach), semantically and phonologically (S/P; apricot), phonologically ( actor), or were unrelated (frost). A control condition was also included (white noise). No age differences were found in the magnitude of the semantic interference effect for young and old, and young adults showed attenuated semantic interference when S/P distractors were presented, but older adults did not. When phonological distractors were presented after the picture, no age differences in facilitation were found. These results are consistent with the Transmission Deficit hypothesis which predicts age differences in performance dependent upon top-down priming to the phonological level (i.e. S/P distractors), but no age differences when processing is bottom-up (i.e. phonological distractors). Overall, these results support an interactive activation model of word production, and suggest that transmission deficits in priming to the phonological level underlie word production deficits in old age.