Investigating the Role of Phonology and Morphology in the Processing and Acceptability of Bilingual Code-Switching

The primary aim of this dissertation was to investigate the often-neglected linguistic domains in the study of bilingual code-switching, namely phonology and morphology. Motivated by empirical and theoretical observations, this dissertation narrowed the focus of study to auxiliary-participle compounds in Spanish-English code-switching. This structure has attracted attention because progressive code-switched phrases are favored over perfect ones in both distribution and comprehension, a pattern that has been interpreted through usage-based explanations. Here, I examined the potential influence that phonological and morphological variables can exert on the asymmetry. Two studies were designed, each isolating a different element from the aspectual compound. Study 1 controlled for and evaluated the role of auxiliary length in different aspect (progressive, estaban vs. perfect, habían - Experiment 1) and same aspect (present perfect, han vs. past perfect, habían - Experiment 2) structures. Study 2 concentrated on participle-level characteristics that are incongruous between English and Spanish past participles, specifically, verbal inflection (regular vs. irregular - Experiment 3) and syllable length (monosyllabic vs. multisyllabic - Experiment 4). Using a combination of online (eye-tracking while reading) and offline (acceptability judgments) tasks, this dissertation revealed that the well-documented aspectual processing asymmetry stems from a methodological confound. The eye-tracking results from Experiments 1 and 2 combined indicate that the lack of preference to switch in [han + English past participle] structures is triggered by the short length of the Spanish auxiliary rather than by aspect, a finding hard to accommodate by experience-based accounts. Acceptability ratings reflect these processing patterns and also suggest a metalinguistic bias to (left) phrase-boundary switching, i.e., at the auxiliary. Even though no significant results were observed for participle length and regularity, a trend emerged that merits further investigation of verbal inflection type. Overall, these findings underscore the role of non-syntactic variables in bilingual sentence processing, with implications for the design of experimental materials and the generalization of results.