The current study examined the neural systems underlying lexically conditioned phonetic variation in spoken word production. Participants were asked to read aloud singly presented words which either had a voiced minimal pair (MP) neighbor (e.g. cape) or lacked a minimal pair (NMP) neighbor (e.g. cake). The voiced neighbor never appeared in the stimulus set. Behavioral results showed longer voice-onset time for MP target words, replicating earlier behavioral results (). fMRI results revealed reduced activation for MP words compared to NMP words in a network including the left posterior superior temporal gyrus, the supramarginal gyrus, inferior frontal gyrus, and precentral gyrus. These findings support cascade models of spoken word production and show that neural activation at the lexical level modulates activation in those brain regions involved in lexical selection, phonological planning, and ultimately motor plans for production. The facilitatory effects for words with minimal pair neighbors suggest that competition effects reflect the overlap inherent in the phonological representation of the target word and its minimal pair neighbor.
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