Decompositional Representation of Morphological Complexity: Multivariate fMRI Evidence from Italian

Area of Science:

• Neuroscience
• Psycholinguistics
• Linguistics

Background:

• Derivational morphology is a key word-formation process, but its neurocognitive underpinnings are not fully understood.
• Previous research suggests derived words are processed as whole units, distinct from combinatorial language processing networks.
• The role of semantic transparency and affix productivity in this process requires further investigation.

Purpose of the Study:

• To investigate the neurocognitive mechanisms of derived word processing.
• To clarify how semantic transparency and affix productivity affect the representation of derived words.
• To determine the neural systems involved in processing derived words based on these factors.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used with a "simple listening" no-task procedure.
• Analyses included univariate and multivariate approaches to examine brain activity.
• The study focused on the Italian lexicon, known for its combinatorial richness.

Main Results:

• Semantic transparency significantly modulated word processing, influenced by affix productivity.
• Opaque derived words, especially with nonproductive suffixes, showed whole-form processing with bilateral frontotemporal activity.
• Semantically transparent words with productive affixes did not exhibit lexical competition, suggesting structured co-representation; transparent words with nonproductive affixes showed intermediate effects.

Conclusions:

• Derived word processing is influenced by semantic transparency and affix productivity.
• Opaque derived words are processed as whole forms within the bihemispheric language system.
• Transparent derived words with productive affixes engage specific left inferior frontal regions, indicating flexible combinatorial and decompositional processing.