Lexical Access Changes Based on Listener Needs: Real-Time Word Recognition in Continuous Speech in Cochlear Implant...

Area of Science:

• Auditory Neuroscience
• Speech Perception
• Lexical Access

Background:

• Word recognition faces challenges due to speech unfolding over time, creating temporary ambiguity.
• Normal hearing (NH) listeners resolve ambiguity via incremental processing and lexical candidate competition.
• Post-lingually deafened cochlear implant (CI) users exhibit similar processes but with delays, potentially impacting multi-word comprehension.

Purpose of the Study:

• To investigate if words in continuous speech (carrier phrases) are processed differently than in isolation.
• To determine if NH listeners and CI users are affected differently by carrier phrases.
• To explore the temporal dynamics of lexical access in CI users versus NH listeners.

Main Methods:

• A Visual World Paradigm experiment tracked eye movements to index lexical candidate activation.
• Participants heard target words in isolation or within non-informative carrier phrases.
• Included 21 post-lingually deafened CI users and 21 NH controls, with replication data from additional participants.

Main Results:

• Both CI users and NH controls were accurate in word recognition, regardless of presentation context.
• CI users demonstrated delayed target fixation and reduced, but longer-lasting, cohort competition compared to NH controls.
• Carrier phrases increased lexical access immediacy for both groups, with no differential effect on CI users.

Conclusions:

• CI users displayed a novel "wait-and-see" profile, delaying lexical access to minimize initial competition.
• CI users sustained competitor activation longer, potentially preserving flexibility and aiding misperception recovery.
• This adaptive lexical processing in CI users reflects a flexible system optimizing for auditory input challenges.