Spoken sentence processing in young and older adults modulated by task demands: evidence from self-paced listening.

Young and older adult listeners paced themselves through recorded sentences, under instructions to recall the sentence verbatim or to respond to comprehension probes. Sentences varied in syntactic complexity and speech rate. Young and older adults paused longer after major syntactic boundaries, an effect that was constant across speech rates but became more pronounced with increasing syntactic complexity. These effects were moderated by listeners' expectations of what they were to do with the linguistic input and by their recent experience with particular tasks. Older adults tended to pause longer in the recall condition, especially when it preceded the comprehension condition. Young adults paused differentially longer at major syntactic boundaries in the comprehension condition, but only when the comprehension condition preceded the recall condition. These findings are discussed in the context of two competing theories of syntactic processing.