Decoding the neural dynamics of within- and between-language lexical competition: A pediatric neurosurgical case report of a Spanish-English bilingual

Spoken word recognition proceeds by immediately activating items in the mental lexicon which match the incoming speech signal. These items compete for recognition over time. In multilinguals, the array of possible lexical competitors includes items across all their languages. Eye-tracking work indicates that the strength of early competitor activation relates to listeners’ proficiency: words from the dominant language outcompete those from the other(s). However, the neural mechanisms that give rise to this effect are not well known. We present a case study of a pediatric neurosurgical patient who was bilingual in English (nondominant) and Spanish (dominant). The participant passively listened to English and Spanish cohort competitors. We used machine learning techniques to decode within- and between-language lexical competition dynamics from the pattern of activity on the superior temporal plane. Spanish words were more robustly decodable than English words, regardless of their role as a target word (the actual word heard on a given trial) or as a competitor (the phonologically related word competing for activation). This is consistent with a Spanish-dominant system—corroborating evidence from eye-tracking—and suggests that activation of cohorts may be in part due to perceptual tuning of early auditory areas for the sounds of a language.