Effects of age on comprehension of complex sentences in adulthood.

This study was designed to determine effects of aging on comprehension of complex sentences. In particular, we were interested in whether normal aging modifies a subsystem of comprehension (i.e., syntactic or semantic) or places unusual demand on working memory related to the distance between constituents that must be integrated. Five age-defined groups of healthy adults were asked questions about thematic roles of nouns in sentences with center-embedded or right-branching subordinate clauses. Results indicated that comprehension accuracy declines after age 60. Although aging did not affect the semantic component, it did affect the syntactic component when evaluated with sentences representing implausible events. There appeared to be an effect of distance between constituents in the 70s decade that was not related solely to embedding of a subordinate clause. Instead of affecting a single component of the language system, normal aging may have an impact on interactions between components.