The Influence of Lexical Characteristics on Sentence Production in Younger and Older Adults

In the study of language production in aging, an important question relates to the relationship between lexical retrieval and syntactic production. Studies have reported changes in syntactic production across the lifespan, but their underlying cause remains unclear. In younger adults, it has been suggested that lexical factors, such as an item‟s semantic or phonological representation influence syntactic production; however, the full nature of this influence remains unclear. Studies investigating the type of sentence produced have found semantic facilitation and phonological interference (e.g., Bock, 1986, 1987), but studies investigating response time (e.g., Meyer, 1996) have found the opposite effects. This investigation sought to examine the influence of lexical level information on sentence production in younger and older adults. This was accomplished by concurrently examining reaction time and sentence type effects. In Experiment 1, 61 adults (mean age: 21.8 years) were presented with pictures and distractor words (unrelated, or semantically or phonologically related). Three stimulus onset asynchronies (SOA) were used (-1000ms, -150ms and 150ms). Participants were required to describe each picture. Using an analysis of variance, response time was compared across the different conditions and using generalized estimating equations, the type of sentence produced and the position of the primed word were compared. In Experiment 2, phonological distractors were excluded, and one SOA (-150ms) was used. Testing involved 83 younger adults (mean age: 22.9 years) and 56 older adults (mean age: 74.7 years). In Experiment 1, semantic distractors resulted in related nouns being produced more often in the subject position. This effect was observed in the analysis of the position of the target noun, but not in the analysis of the type of sentence produced. There were no effects of phonological distractors. In Experiment 2, semantic distractors influenced the type of sentence produced for both age groups. The groups differed only in error production. No reaction time effects were observed in either experiment. This investigation successfully demonstrated an influence of lexical level information on the syntactic productions of younger and older adults. The two groups were similar in their productions, suggesting that aspects of syntactic production are preserved in older adults.Ph