New patterns of pathological language mixing in bilingual aphasia

A central challenge in bilingual aphasia research is the absence of clear markers that distinguish pathological language mixing (PLM) from mixing used as a compensatory mechanism, leaving ongoing debates unresolved. Also, prior work suggests that PLM occurs primarily during retrieval of open-class words and increases with utterance length during structured tasks, yet these findings, and the hesitation behaviors accompanying PLM, remain largely untested in spontaneous speech.

This study examines PLM in Patient P3, a 59-year-old female bilingual speaker of Spanish and English with severe Broca's aphasia who showed extensive mixing and reported significant communicative disruption as a result. She was administered the Western Aphasia Battery-Revised in both languages and transcribed samples from her response to narrative prompts were coded for word class and language mixing, and hesitation durations were acoustically analyzed.

P3 mixed closed-class words more frequently than open-class words. PLM frequency was unrelated to utterance length, and longer hesitations preceded non-target language intrusions, indicating increased retrieval cost. P3 showed elevated Aphasia Quotients in both languages when cross-language responses were computed, suggesting symmetric (bidirectional) mixing rather than assymetric (unidirectional) compensatory intrusion into the weaker language.

Together, these results propose symmetric language mixing and higher hesitation duration preceding non-target intrusions as potential markers of control deficits in bilingual aphasia.