Recognizing Speech in a Novel Accent: The Motor Theory of Speech Perception Reframed

The motor theory of speech perception holds that we perceive the speech of another in terms of a motor representation of that speech. However, when we have learned to recognize a foreign accent, it seems plausible that recognition of a word rarely involves reconstruction of the speech gestures of the speaker rather than the listener. To better assess the motor theory and this observation, we proceed in three stages. Part 1 places the motor theory of speech perception in a larger framework based on our earlier models of the adaptive formation of mirror neurons for grasping, and for viewing extensions of that mirror system as part of a larger system for neuro-linguistic processing, augmented by the present consideration of recognizing speech in a novel accent. Part 2 then offers a novel computational model of how a listener comes to understand the speech of someone speaking the listener's native language with a foreign accent. The core tenet of the model is that the listener uses hypotheses about the word the speaker is currently uttering to update probabilities linking the sound produced by the speaker to phonemes in the native language repertoire of the listener. This, on average, improves the recognition of later words. This model is neutral regarding the nature of the representations it uses (motor vs. auditory). It serve as a reference point for the discussion in Part 3, which proposes a dual-stream neuro-linguistic architecture to revisits claims for and against the motor theory of speech perception and the relevance of mirror neurons, and extracts some implications for the reframing of the motor theory

The influence of orthography on phonemic knowledge: An experimental investigation on German and Persian

This study investigated whether the phonological representation of a word is modulated by its orthographic representation in case of a mismatch between the two representations. Such a mismatch is found in Persian, where short vowels are represented phonemically but not orthographically. Persian adult literates, Persian adult illiterates, and German adult literates were presented with two auditory tasks, an AX-discrimination task and a reversal task. We assumed that if orthographic representations influence phonological representations, Persian literates should perform worse than Persian illiterates or German literates on items with short vowels in these tasks. The results of the discrimination tasks showed that Persian literates and illiterates as well as German literates were approximately equally competent in discriminating short vowels in Persian words and pseudowords. Persian literates did not well discriminate German words containing phonemes that differed only in vowel length. German literates performed relatively poorly in discriminating German homographic words that differed only in vowel length. Persian illiterates were unable to perform the reversal task in Persian. The results of the other two participant groups in the reversal task showed the predicted poorer performance of Persian literates on Persian items containing short vowels compared to items containing long vowels only. German literates did not show this effect in German. Our results suggest two distinct effects of orthography on phonemic representations: whereas the lack of orthographic representations seems to affect phonemic awareness, homography seems to affect the discriminability of phonemic representations

Lexical and sub-lexical knowledge influences the encoding, storage, and articulation of nonwords

Nonword repetition (NWR) has been used extensively in the study of child language. Although lexical and sub-lexical knowledge is known to influence NWR performance, there has been little examination of the NWR processes (e.g., encoding, storage, articulation) that may be affected by lexical and sub-lexical knowledge. We administered 2- and 3-syllable spoken nonword recognition and nonword repetition tests on two independent groups of 31 children (M=5;07). Spoken nonword recognition primarily involves encoding and storage, whereas NWR involves an additional articulation process. The influence of lexical and sub-lexical knowledge was determined by examining the amount of lexical errors produced. There was a clear involvement of long-term lexical and sub-lexical knowledge in both spoken nonword recognition and NWR. In spoken nonword recognition, twice as many errors involved selecting a foil that contained a lexical item (e.g., yashukup) over a foil that contained only nonsense syllables (e.g., yashunup). In repetition, over 30% of errors changed a nonsense syllable to a lexical item. Our results show that long-term lexical and sub-lexical knowledge is pervasive in NWR – any explanation of NWR performance must therefore consider the influence of lexical and sub-lexical knowledge throughout the whole repetition process, from the encoding of nonwords to the articulation of them

Spanish epenthesis: Formal and performance perspectives

published or submitted for publicationis peer reviewe

A computational simulation of children's performance across three nonword repetition tests

The nonword repetition test has been regularly used to examine children’s vocabulary acquisition, and yet there is no clear explanation of all of the effects seen in nonword repetition. This paper presents a study of 5-6 year-old children’s repetition performance on three nonword repetition tests that vary in the degree of their lexicality. EPAM-VOC, a model of children’s vocabulary acquisition, is then presented that captures the children’s performance in all three repetition tests. The model represents a clear explanation of how working memory and long-term lexical and sub-lexical knowledge interact in a way that is able to simulate repetition performance across three nonword tests within the same model and without the need for test specific parameter settings

The impact of visual cues and lexical knowledge on the perception of a non-native consonant contrast for Colombian adults

The study investigates the impact of visual cues and lexical knowledge on the identification of a nonnative phonemic contrast. Twenty native Colombians were tested on an identification task involving 16 minimal pairs of English words, produced by four English speakers, contrasting in the presence of /b/ or /v/ in initial or medial position. The test was run in three conditions: audiovisual (AV), audio only (A) or visual only (V). Prior to the identification task, their knowledge of the lexical items was evaluated; they were also recorded while reading the words. Mean identification scores were higher for the AV than the A condition, but V and AV scores not differ. Relative to previous /b/-/v/ studies with Peninsular Spanish speakers, Colombians relied more heavily on visual cues in their identification of /b/-/v/. Although there was a trend for identification scores to be higher for known lexical items, this effect was not statistically significant. Finally, production accuracy for the /b/-/v/ contrast was not correlated with perception accuracy, but production tended to be more accurate in speakers with better lexical knowledge. The visual weighting results suggest that the degree of visual bias in speech perception may be ‘culture-specific’ rather than merely ‘language-specific’

The distractor frequency effect in picture–word interference: evidence for response exclusion

In 3 experiments, subjects named pictures with low- or high-frequency superimposed distractor words. In a 1st experiment, we replicated the finding that low-frequency words induce more interference in picture naming than high-frequency words (i.e., distractor frequency effect; Miozzo & Caramazza, 2003). According to the response exclusion hypothesis, this effect has its origin at a postlexical stage and is related to a response buffer. The account predicts that the distractor frequency effect should only be present when a response to the word enters the response buffer. This was tested by masking the distractor (Experiment 2) and by presenting it at various time points before stimulus onset (Experiment 3). Results supported the hypothesis by showing that the effect was only present when distractors were visible, and if they were presented in close proximity to the target picture. These results have implications for the models of lexical access and for the tasks that can be used to study this process