Preserved communicative use of shared knowledge by individuals with mild Parkinson’s disease

Using shared knowledge in conversation is key to successful social communication. Speakers adjust their language with respect to the partner’s knowledge, for example, producing shorter descriptions for familiar listeners, and longer descriptions for unfamiliar listeners. For example, individuals from Iowa may refer to the local university, University of Iowa, as the “UI.” However, if they are speaking to a listener from outside the state, they would need to clarify the university with the full name and its location to ensure understanding (“University of Iowa in Iowa City”). This process is called audience design. Previous research has demonstrated that individuals with memory deficits for facts and events have the preserved ability for audience design and suggested that this type of memory is not required in audience design. It is therefore implicated that audience design is a more implicit memory process and may rely on nondeclarative memory, which is responsible for storing processes and sequences. In the current study, the social language abilities of individuals with mild Parkinson’s disease and its associated, nondeclarative memory impairment is investigated.

The current study examined expression length in the descriptions of abstract images across conversation rounds with the same partner or a new partner. No significant differences were found between the healthy control participants and individuals with Parkinson’s disease for establishing and using common labels. However, individuals with Parkinson’s disease were found to use shorter descriptions overall. Both memory systems are therefore implicated in audience design, with the ability to compensate for impairments in either. Shorter descriptions may be attributed to motor difficulties, as well as challenges with language formulation deficits, including in the production of complex, grammatical sentences, due to impairments in nondeclarative memory. The study is an initial step in deeper understanding of memory systems and social language.