Facilitation and interference of phoneme repetition and phoneme similarity in speech production

Speakers know that it is hard to produce tongue-twister-like utterances involving repeated and similar phonemes (“She sells socks in a small shoe shop”). While utterances involving phonologically similar phonemes consistently give rise to speech errors, repeated phonemes have been shown to interfere as well as to facilitate production. Here we try to shed light on this paradox by investigating brain processes underlying planning utterances involving similar and repeated phonemes (tongue-twister-like) and utterances with only repeated phonemes elicited with picture naming during electroencephalographic/event-related potentials (EEG/ERP) recording. Tongue-twister-like utterances increased error rates while repeated onset phonemes decreased reaction times. Both types of utterances modulated ERPs after 370 ms following picture onset by shortening a period of stable electrophysiological pattern. Another microstate was lengthened for tongue-twister-like utterances only, wiping out the timing difference of the previous microstate. These results indicate priming of repeated phonemes and cost of encoding similar phonemes, both phenomena co-occurring in tongue-twisters.