The role of morphological structure in the processing of complex forms: evidence from Setswana deverbative nouns

The morphological structure of poly-morphemic words (e.g. government) can affect processing, but it is unclear whether this effect is due to morphological structure or combined formal/orthographic and semantic effects. Setswana, a Bantu language, allows us to explore morphological, formal, and semantic effects: It has a noun derivation with an agglutinative agentive affix (Class-1, mo-rer-i “preacher”) and a noun derivation with vowel changes and little form-overlap (Class-9, ther-o “sermon”) that both apply to verbs (rer-a “preach”). In our masked-priming experiments (SOA = 60 ms), Class-9-forms were even more effective as primes for verbs than Class-1-forms, despite reduced formal overlap, suggesting that abstract morphological structure affects processing independently of formal or semantic relationships. Moreover, Class-1-targets showed reduced priming, indicating that unprimed morphological target material (the affix) reduces priming.