Influence of perceptual strength on conceptual processing : Investigation in aging and in lexical-semantic decisions

While the intervention of the sensorimotor system in semantic processing has already been demonstrated in young adults and more recently in children, very few studies have investigated this question in aging. Due to the numerous cognitive, sensory, and motor modifications encountered in aging and the relationships established between the sensorimotor and conceptual systems, it is particularly interesting to study the life-long evolution of semantic representations in this population. The purpose of this study is to explore the effect of perceptual strength (PS) and aging on lexical-semantic processing. We compare data from 32 young healthy adults and 36 healthy older adults in a lexical decision task (experiment 1) and a semantic decision task (experiment 2) that contrast words with high PS and low PS. In experiment 1, high PS words tend to be processed faster similarly in both groups, while in experiment 2 (imageability decision) the young and older adults show opposite patterns, the older adults being faster for low PS. The results are discussed with regards to the demand of the task that influences processing in aging. The imageability task, probably involving direct activation of the modal simulation system, seems to suggest a modification of perceptual/semantic processing in aging.