Tomato-tomahto: Phonological representations vs. surface-level features in speech planning

Speakers often lengthen the duration of a word when it shares initial phonological segments with a previously uttered word (e.g., candy and candle). One explanation for this is that words with initial similarity affect phonological encoding during sequence planning, yet it is unclear whether this similarity is phonetic or phonological. We manipulated phonetic differences by using a dialect variant: the pin-pen merger in American English. Participants completed an event description task in three experiments. We manipulated whether the participant's target vowel ([ɪ] or [ɛ]) either phonetically matched or mismatched the vowel of the prime speaker, depending on the participant's dialect. In the second experiment, we introduced a control vowel in the prime word ([æ] vs. [ɛ]). Participants in both dialect groups lengthened target words when they shared an initial phoneme, even when the vowel of the overlapping prime word was not shared across dialects. In the third experiment, we replicated this finding in a larger cohort of non-merger participants. All three experiments showed word lengthening despite the phonetic realization of phonemes, suggesting this effect is driven by phonological representations rather than surface-level pronunciations.