Gemination and degemination in English prefixation: Phonetic evidence for morphological organization

•In casual speech both English un- and in- geminate, contra common assumptions.•Morphological segmentability influences the duration of the prefixal nasals.•The strength of morphological boundaries may impact on the durational properties of complex words.•This challenges standard assumptions in morphological theory and speech production models.

This paper addresses the problem of morpho-phonological variability and the role of phonetic detail in morphologically complex words by investigating the gemination behavior of the English prefixes un- and in-. Traditionally, it is assumed that un- geminates while in- degeminates, but empirical studies are rare and not conclusive. This paper presents the first study that uses data from natural speech (Switchboard Corpus, Godfrey and Holliman 1997). It is shown that both prefixes geminate, contra large parts of the literature. Furthermore, there is a difference in nasal duration between un-, negative in- and locative in-. The more segmentable the prefix the longer the nasal duration. The results challenge widely-shared assumptions in morphological theory, lexical phonology and models of speech production, and support models in which the strength of morphological boundaries may impact on the durational properties of complex words.