A double dissociation between plural and possessive "s": Evidence from the Morphosyntactic Generation test

Area of Science:

• Neurolinguistics
• Psycholinguistics
• Cognitive Neuroscience

Background:

• Individuals with aphasia often exhibit difficulties in producing bound inflectional morphemes, including noun plurals and possessives.
• Aphasia research frequently observes greater challenges in marking possession compared to plurality.

Purpose of the Study:

• To investigate the production of plural and possessive morphemes in individuals with aphasia using a novel assessment tool.
• To explore the relationship between clinical profiles and specific morphosyntactic strengths and weaknesses.
• To examine evidence for a functional double dissociation between plural and possessive marking.

Main Methods:

• Utilized the Morphosyntactic Generation test, a new tool designed for language elicitation.
• Assessed participants with primary progressive aphasia and those in acute and chronic stages post-left hemisphere stroke.
• Analyzed group performance and individual case patterns for plural and possessive morpheme production.

Main Results:

• Group analyses indicated stronger performance in producing plurals compared to possessives.
• Identified a subset of individuals exhibiting the inverse pattern, with better possessive than plural production.
• These individual differences challenge theories attributing possessive difficulty solely to cognitive-linguistic complexity.

Conclusions:

• The findings support a functional double dissociation between the processing of plural and possessive markers.
• Morphosyntactic impairment underlies the observed deficits in morpheme production.
• Further research is required to elucidate the differential sensitivity of plural and possessive markers to neurological language disorders.