Comparing linguistic complexity and efficiency in conversations from stimulation and conversation therapy in aphasia

Efficacy studies have demonstrated the benefit of group conversation therapy for a person with aphasia (PWA). However, a PWA typically participates in individual therapy prior to group therapy. Stimulation therapy (ST) is the most common type of individual aphasia therapy. Ultimately, the outcome of therapy is to enable the PWA to communicate effectively with others, which suggests the need for conversation therapy (CT). Little efficacy data exist to demonstrate the benefit of CT between a PWA and a clinician, in part because no clear treatment outcome measures have been established. More information is needed to identify optimal ways to measure CT outcomes.

To identify ways to measure CT outcomes and to determine if there is a change in linguistic complexity and total talk time during conversation, samples were taken during CT and ST in two PWAs.

Seventeen 6-min conversational samples per PWA were analyzed from a prior single-subject AB₁ AB₂ A alternating treatment study with randomized ordering of interventions across participants. Data were analyzed for seven measures of linguistic complexity using Systematic Analysis of Language Transcripts (SALT). Efficiency was measured using correct information units (CIUs) per minute and total talk time.

Per cent of complex utterances and propositional density were higher following CT. Four out of seven linguistic measures increased following ST. Total talk time was significantly greater for one PWA during CT compared with ST. No differences were found in CIUs/min across treatment types.

Linguistic complexity and efficiency appear to be conversational treatment outcome measures that are sensitive to change, which researchers might consider using.