Partner-Specific Audience Design in Parkinson's Disease: Insights From In-Person and Virtual Modalities

Successful conversation depends on audience design-tailoring utterances to a partner's knowledge. Parkinson's disease (PD) is linked to speech motor and pragmatic impairments, yet it remains unclear whether speakers with PD retain partner-specific audience design. We tested two competing predictions. If previously reported pragmatic deficits generalize, speakers with PD should show attenuated partner sensitivity. If adaptive mechanisms remain intact, audience design should be preserved, particularly in goal-directed interactions.

Two referential communication experiments included two phases: sorting (establishing shared labels) and test (assessing partner-specific adaptation) in a single session. Audience design was measured via (a) expression length and (b) use of definite articles (a motor-independent marker of shared knowledge). Experiment 1 (eight participants with PD, 16 comparison participants) used a primarily virtual dialogue format, with participants interacting with one partner at a time (either a familiar partner or an unfamiliar partner). Experiment 2 (15 participants with PD, 17 comparison participants) was conducted in person and included both dialogue and multiparty formats, alternating between familiar and unfamiliar partners.

Across experiments, individuals with mild PD shortened expressions and increased definite article use during sorting, indicating successful establishment of shared labels. During test, they produced shorter, more definite expressions for familiar than unfamiliar partners, demonstrating preserved sensitivity to shared knowledge. In Experiment 1, individuals with PD showed less adaptation when describing old items to familiar partners than neurotypical comparison participants. This difference was not observed in Experiment 2, suggesting that in-person interaction supports pragmatic adaptation. A joint analysis revealed a modality effect, such that only the PD group produced shorter expressions in virtual than in-person settings during sorting while establishing common ground with the familiar partner.

Audience design is largely preserved in early PD, including in multiple party contexts. However, communication modality influences how fully these skills are expressed, emphasizing the importance of supportive cues in remote settings.