Adult Age Differences in the Benefit of Syntactic and Semantic Constraints for Sentence Processing

Verbal working memory-intensive sentence processing declines with age. This might reflect older adults' difficulties with reducing the memory load by grouping single words into multiword chunks. Here we used a serial order task emphasizing syntactic and semantic relations. We evaluated the extent to which older compared with younger adults may differentially use linguistic constraints during sentence processing to cope with verbal working memory limitations. Probing syntactic-semantic interactions, age differences were hypothesized to be confined to the use of syntactic constraints and to be accompanied by an increased reliance on semantic information. Two experiments varying in verbal working memory demands were conducted: the sequence length was increased from eight items in Experiment 1 to 11 items in Experiment 2. We found the use of syntactic constraints to be compromised with aging, while the benefit of semantic information for sentence processing was comparable across age groups. Hence, we suggest that semantic information processing may become relatively more important for successful sentence processing with advancing adult age, possibly inducing a syntactic-to-semantic-processing strategy shift.