Across experimental designs and in historical linguistics, we found that complexity in linguistic morphological structure plays a critical role in processing and change. Under (A), we experimentally examined morphological complexity in Bengali, English and German using EEG, behavioural, and eye-tracking techniques. Our results showed that morpheme complexity and constraints on morpheme sequences play a definite role in processing. In Bengali, processing asymmetries of affixed words in behavioural tasks were attributable to differences in inhibition from the phonological cohort and also to the salience of morpheme boundaries. Processing asymmetries (using an MMN paradigm) were also found for English ablaut verbs (e.g. get ~ got; sit ~ sat; *gef ~ *gof, *sif ~ *saf). Our EEG results showed that both for real words, as well as pseudowords, the phonological representations affected processing. Height mismatched in both directions for the sit ~ sat pair, while place was asymmetric in get ~ got pair, both of which were reflected in MMN patterns. Pseudowords behaved in the same way, indicating that the phonological representations of individual segments remained constant. Predicted symmetries in tonal dissimilation in Mandarin were also revealed in EEG patterns, and pitch accent tonal contrasts in Swedish showed that representations of the tones affected processing (revealed in eye-tracking) for monolinguals and bilinguals.
For (B), we considered the notions about the way in which analogical extensions and prosodic constraints interact even with loanwords. By focusing on medieval stages of English, Dutch and German, we found that metrical patterns in Germanic have consistently remained on the first syllable regardless of phonological alternations. Romance loans, however, caused havoc in the individual metrical systems, particularly due to affixed words. We have shown that, despite the large number of loans and substantial increase in complex words in the lexicons, the basic foot structure has remained trochaic. The critical difference is that English maintains its preference not to stress final syllables, making the main stress fall away from the right edge. In contrast, German and Dutch do allow final stressed syllables if they have the relevant weight. This suggests that all three languages have maintained their basic foot structure and presence or absence of heavy syllables at the right edge of words, despite the onslaught of loans.
For (C), our results supported the idea that compounding in English and Bengali carry similar lexical and morphological properties, but prosodically, the outputs can be very different. We also found evidence through naming tasks that visual concatenation (e.g. time zone vs. timeline) is not a reliable indicator of compounding in English: prosodic output can be very different from the visual input.
