Behavioral and modeling evidence suggests that words compete for recognition during auditory word identification, and that phonological similarity is a driving factor in this competition. The present study used event-related potentials [ERPs] to examine the temporal dynamics of different types of phonological competition (i.e., cohort and rhyme). ERPs were recorded during a novel picture-word matching task, where a target picture was followed by an auditory word that either matched the target (CONE-cone), or mismatched in one of three ways: rhyme (CONE-bone), cohort (CONE-comb), and unrelated (CONE-fox). Rhymes and cohorts differentially modulated two distinct ERP components, the Phonological Mismatch Negativity [PMN] and the N400, revealing the influences of pre-lexical and lexical processing components in speech recognition. Cohort mismatches resulted in late increased negativity in the N400, reflecting disambiguation of the later point of miscue and the combined influences of top-down expectations and misleading bottom-up phonological information on processing. In contrast, we observed a reduction in the N400 for rhyme mismatches, reflecting lexical activation of rhyme competitors. Moreover, the observed rhyme effects suggest that there is interaction between phoneme-level and lexical-level information in the recognition of spoken words. The results support the theory that both levels of information are engaged in parallel during auditory word recognition in a way that permits both bottom-up and top-down competition effects. Keywords Perception; Auditory processing; Event related potentialsIn understanding spoken language listeners need to both perceive incoming auditory information and access a semantic representation of that input. Although speech is understood quite rapidly and effortlessly, the cognitive processing involved in spoken word recognition is not trivial. In order to recognize what is being said, acoustic information must be translated into a phonological code, segmented into discrete words, and integrated with both the immediate context and prior knowledge such as word familiarity and contextual CIHR Author ManuscriptCIHR Author Manuscript CIHR Author Manuscript cues. Consistent with this, studies have revealed a range of factors that influence auditory word recognition (Luce & Pisoni, 1998;Norris, McQueen, & Cutler, 2000;Frauenfelder & Tyler, 1987;McClelland & Elman, 1986). These can be coarsely divided into two categories: those revealing the influence of 'pre-lexical' cues related to acoustic and phonological features, and those indexing the role of 'lexical' knowledge that denotes lexical-level influences such as frequency. There is significant ongoing discussion about exactly how auditory words are recognized, focusing on how and when these different types of information are accessed during the time course of processing, and furthermore, the extent to which these interact.Evidence suggests that spoken words are processed as speech unfolds, and that phonologically similar items ...

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.

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Page 1 AbstractThe present study was designed to investigate the electrophysiological consequences of a mismatch between initial phoneme expectations and the actual spoken input. Participants were presented with a word/nonword prompt with the instruction to delete the initial sound (e.g., snap without the /s/; snoth without the /s/) and determine the resulting segment. Following the prompt, an aurally presented response that matched/mismatched expectations (e.g., nap/tap; noth/toth) was presented. The Phonological Mapping Negativity (PMN), a response associated with phonological processing, was largest to mismatching responses, and was not dependent on the lexical status of response items. An N400-like response was also largest to mismatching responses; however, in contrast to the PMN, the N400-like response differentiated mismatching words from mismatching nonwords. These findings highlight a functional dissociation between the PMN and N400, and establish the PMN as a neural marker representing the goodness-of-fit between initial phoneme expectations and the actual spoken input.

We used event-related potentials (ERPs) to compare auditory word recognition in children with specific language impairment (SLI group; N=14) to a group of typically developing children (TD group; N=14). Subjects were presented with pictures of items and heard auditory words that either matched or mismatched the pictures. Mismatches overlapped expected words in word-onset (cohort mismatches; see: DOLL, hear: dog), rhyme (CONE -bone), or were unrelated (SHELL -mug). In match trials, the SLI group showed a different pattern of N100 responses to auditory stimuli compared to the TD group, indicative of early auditory processing differences in SLI. However, the phonological mapping negativity (PMN) response to mismatching items was comparable across groups, suggesting that just like TD children, children with SLI are capable of establishing phonological expectations and detecting violations of these expectations in an online fashion. Perhaps most importantly, we observed a lack of attenuation of the N400 for rhyming words in the SLI group, which suggests that either these children were not as sensitive to rhyme similarity as their typically developing peers, or did not suppress lexical alternatives to the same extent. These findings help shed light on the underlying deficits responsible for SLI.

The data suggest that children with dyslexia have impairments in integrating phonological information into word-level representations. The results suggest that speech perception difficulties in dyslexia might have consequences for processing auditory words.

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