Congruent Prosody Reduces Cognitive Effort in Memory for Spoken Sentences: A Pupillometric Study with Young and Older Adults.

Background: In spite of declines in working memory and other processes, older adults generally maintain good ability to understand and remember spoken sentences. In part this is due to preserved knowledge of linguistic rules and their implementation. Largely overlooked, however, is the support older adults may gain from the presence of sentence prosody (pitch contour, lexical stress, intra-and inter-word timing) as an aid to detecting the structure of a heard sentence.

Methods: Twenty-four young and 24 older adults recalled recorded sentences in which the sentence prosody corresponded to the clausal structure of the sentence, when the prosody was in conflict with this structure, or when there was reduced prosody uninformative with regard to the clausal structure. Pupil size was concurrently recorded as a measure of processing effort.

Results: Both young and older adults' recall accuracy was superior for sentences heard with supportive prosody than for sentences with uninformative prosody or for sentences in which the prosodic marking and causal structure were in conflict. The measurement of pupil dilation suggested that the task was generally more effortful for the older adults, but with both groups showing a similar pattern of effort-reducing effects of supportive prosody.

Conclusions: Results demonstrate the influence of prosody on young and older adults' ability to recall accurately multi-clause sentences, and the significant role effective prosody may play in preserving processing effort.