Age-related differences in speech production: Evidence from graph analyses

Storytelling is a vital aspect of language processing requiring successful integration of characters, events, and actions. Cohesive stories include the necessary information to transition between utterances and convey the overall gist. Although older adults produce more off-topic speech, it remains unclear how age affects narrative organization across discourse contexts. Additionally, broader cognitive declines in aging, like differences in executive function, may contribute to discourse production. The present study examined discourse production using computational speech graph analyses in 268 healthy adults aged 20-81 years old. Participants completed two speech production tasks differing in contextual support: a picture book description and an open-ended prompt. Speech graphs quantified connectedness by modeling words as nodes and their sequential relationships as edges, capturing local repetition and longer-range integration within discourse. Results indicated that age was correlated with increased repetition and less connected speech. There was also a main effect of task where the picture book task elicited denser, more interconnected speech with greater reintegration across the narrative, while the open-ended prompt elicited speech that advanced more sequentially, with fewer cycles linking earlier and later portions of the narrative. Critically, age-related differences in connectedness were most evident in the open-ended prompt and were independent of executive function, suggesting a gradual shift toward more locally constrained speech in later adulthood, particularly when speech must be generated and organized without external support. Importantly, graph-based measures were sensitive to these subtle organizational shifts, highlighting their potential to complement established discourse metrics and deepen our understanding of speech across adulthood.