Semantic Typicality of Affixes Facilitates Word Processing: MEG Evidence From Arabic

Upon reading a word, we decompose it into meaningful parts-morphemes. Even if novel, we can derive a likely meaning for it based on how its parts typically behave. Given the typical meaning of affix "-ery," we may guess that a bottlery is a place to make bottles, although we may alternatively guess that it is the craft of bottle making. In this study, we operationalize this feature-an affix's semantic typicality-to investigate affix semantics' role in word processing. Using a lexical decision task and a double dissociative design in an MEG setting, we took advantage of Arabic's highly productive word-pattern derivational system to investigate the role of meaning typicality for derivational morphology. We contrasted one affix typically denoting tools and atypically places with another affix having the reverse denotation pattern. We found higher activity for typical-meaning words in the temporal pole, inferior temporal gyrus, and middle temporal gyrus at an earlier time window than previously associated with semantic processing. Additionally, we replicated results on noun/verb ambiguity, where ambiguous words had higher activity in the fusiform gyrus and throughout the temporal lobe. Our results on lexicality-contrasting words versus nonwords-were also consistent with previous literature. A finer-grained distinction between pseudowords with real roots versus pseudoroots further allowed us to explore the role of affixes in processing in the temporal pole and the inferior frontal cortex. Overall, our study contributes importantly to findings on affix semantic processing and contributes generally to growing findings on different stages of morphological decomposition.