The relationship between trained ratings and untrained listeners' judgments of global coherence in extended monologues

Global Coherence and Cognition in Parkinson's Disease

PURPOSE

This study compared global coherence (GC) in individuals with Parkinson's disease (PD) to a healthy older adult (HOA) group during single (sitting) and dual (stationary cycling) tasks. Additionally, it explored the relationship between GC and cognition in PD.

METHOD

Thirty-seven individuals with PD and 19 HOAs participated in the prospective, cross-sectional study. Participants completed discourse monologues elicited using published prompts while seated and while pedaling a stationary bicycle. Four rating levels of GC were analyzed (GC1 = no relationship to the topic, GC2 = remote relationship, GC3 = conditional relationship, and GC4 = complete relationship) using a published protocol with good interrater reliability and test-retest stability. Participants completed a battery of cognitive tasks, from which four latent factors were extracted: processing speed, working memory, inhibition, and updating.

RESULTS

Linear mixed modeling identified significant effects of GC level and GC level interactions with group, processing speed, and inhibition. The Group × GC Level interaction reflected that the PD group had a higher proportion of GC2 and GC1 utterances and fewer GC4 utterances than the HOA group. No differences between single and dual task conditions were found. Faster speed of processing predicted more GC4 utterances, whereas slower speed of processing predicted more G1 utterances. Better inhibition predicted fewer GC2 utterances. Group also predicted GC4 and GC2 proportions.

CONCLUSIONS

Individuals with PD experienced greater difficulties with GC than HOAs. Processing speed and inhibition contributed significantly to GC across groups. Analysis of GC should be considered an informative addition to assessment of communicative effectiveness in PD.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.20416056.

Measuring Global Coherence in People With Aphasia During Unstructured Conversation

Purpose Global coherence is an essential macrolinguistic discourse skill that speakers use to formulate discourse to convey meaning with maintenance to a topic. When global coherence is poor, the listener's ability to understand how the discourse makes sense as a whole is diminished. Measures exist to evaluate global coherence in people with aphasia during monologue tasks (e.g., picture description). The aim of the current research is to develop such a measure for unstructured conversation and to explore how global coherence is impacted by aphasia during conversation. A global coherence measure for conversation is required because markedly different cognitive and linguistic demands are made for production of different types of discourse. Thus, a structured monologue measure cannot be used with validity for unstructured conversation. To adequately evaluate global coherence during conversation, a measure specific to the demands of conversation is required. Method We adapted the 4-point Global Coherence Scale (Wright & Capilouto, 2012; Wright et al., 2013), a monologue-level measure of global coherence to conversation, resulting in the 4-point Global Coherence Scale in unstructured conversation (GCSconv). We conducted statistical evaluation of the reliability/stability of the 4-point GCSconv in 18 unstructured conversations held by nine people with aphasia. Utterances with low global coherence scores were classified following a recent methodology to describe how breakdown in these utterances contributed to diminished global coherence (Hazamy & Obermeyer, 2019). Results The 4-point GCSconv demonstrated excellent inter/intrarater reliability and test-retest stability. Nonspecific language and off-topic comments contributed most frequently to lowered global coherence. Conclusions Findings suggest the 4-point GCSconv may be a feasible and reliable measure of global coherence in conversation. This measure adds to a core of emerging reliable discourse measures for conversation. As such, it has potential to inform assessment and treatment of everyday conversation and to investigate the relationship of global coherence in structured monologue and unstructured conversation. Supplemental Material https://doi.org/10.23641/asha.12469187.