Influence of phonological expectations during a phoneme deletion task: evidence from event-related brain potentials.

Several studies have identified a negativity [the phonological mismatch negativity (PMN)] preceding the N400 during auditory sentence comprehension. The present study investigated whether the PMN reflects a prelexical or lexical stage of spoken word recognition. Event-related brain potentials (ERPs) were recorded to investigate phonological processing independently from lexical/semantic influences during a task requiring metalinguistic analysis of speech stimuli. Participants were instructed to omit the initial phoneme from a word ("clap" without the/k/) after which they heard a correct (lap) or incorrect (cap, ap, nose) answer. The PMN (peaking at 270 ms) was largest to incorrect items and did not differentiate between items that shared the same rime and items that were phonologically unrelated to the correct choice. Further, the PMN did not differ between word (cap) and nonword (ap) choices. The P300 was largest to correct items but was also seen to choices that rhymed with the correct answer. It is concluded that the PMN serves as a neural marker for the analysis of acoustic input merging with prelexical phonemic expectations.