On the time course of lexical stress priming in speech production: Behavioral and ERPs evidence from a free-stress language

- We examined the time course of lexical stress encoding in a free-stress language.
- We measured event-related brain potentials (ERPs) during stress priming.
- Stress dominance facilitates whereas prime-target stress congruency delays responses.
- ERP show that stress effects occur during the stage of phonological encoding.
- Surprisingly ERPs for dominant and non-dominant stress primes diverged from 150 ms.

The goal of the present research was to study the time course of lexical stress encoding in a free-stress language with unpredictable stress. To this aim we measured event-related brain potentials (ERPs) during lexical priming. Participants named pictures bearing either the dominant or non-dominant stress pattern, and preceded by either a congruent or an incongruent word prime (e.g., CInema-FRAgola'cinema-strawberry' vs. benZIna-FRAgola'petrol-strawberry'). Behavioral results show that participants were slower in naming targets that had the same stress pattern as the prime, and were also faster in producing words with the dominant stress pattern in the language. The electrophysiological results show that both the effects are compatible with the time course of phonological encoding in speech production. Surprisingly, a dominant stress effect occurred in the ERPs elicited by the primes, with a larger positivity for non-dominant stress words in a 150-250 ms time-window. The pattern of results indicates that during speech production: a) the system is sensitive to the stress patterns distribution; b) the automatic pre-activation of a metrical frame may interfere with the phonological encoding of a to-be-uttered word.