Lexical and child-related factors in word variability and accuracy in infants

The present study investigated the effects of lexical age of acquisition (AoA), phonological complexity, age and expressive vocabulary on spoken word variability and accuracy in typically developing infants, aged 1;9–3;1. It was hypothesized that later-acquired words and those with more complex speech sounds would be produced more variably and less accurately than earlier-acquired words and those with less complex speech sounds. It was also hypothesized that word variability would decrease and word accuracy would increase with increasing age and vocabulary knowledge. Participants' productions of 20 target words, experimentally controlled for AoA and phonological complexity, were audio-recorded during a play session. Results revealed a nonsignificant effect of AoA on variability and accuracy, a significant effect of phonological complexity on variability and accuracy, a significant effect of age on variability and accuracy and a significant effect of vocabulary on variability. Theoretical and clinical implications are discussed.     

Electrophysiological evidence of early word learning

Around their first birthday infants begin to talk, yet they comprehend words long before. This study investigated the event-related potentials (ERP) responses of nine-month-olds on basic level picture–word pairings. After a familiarization phase of six picture–word pairings per semantic category, comprehension for novel exemplars was tested in a picture–word matching paradigm. ERPs time-locked to pictures elicited a modulation of the Negative Central (Nc) component, associated with visual attention and recognition. It was attenuated by category repetition as well as by the type–token ratio of picture context. ERPs time-locked to words in the training phase became more negative with repetition (N300–600), but there was no influence of picture type–token ratio, suggesting that infants have identified the concept of each picture before a word was presented. Results from the test phase provided clear support that infants integrated word meanings with (novel) picture context. Here, infants showed different ERP responses for words that did or did not align with the picture context: a phonological mismatch (N200) and a semantic mismatch (N400). Together, results were informative of visual categorization, word recognition and word-to-world-mappings, all three crucial processes for vocabulary construction.     

The phonological memory profile of preschool children who make atypical speech sound errors

Previous research indicates that children with speech sound disorders (SSD) have underlying phonological memory deficits. The SSD population, however, is diverse. While children who make consistent atypical speech errors (phonological disorder/PhDis) are known to have executive function deficits in rule abstraction and cognitive flexibility, little is known about their memory profile. Sixteen monolingual preschool children with atypical speech errors (PhDis) were matched individually to age-and-gender peers with typically developing speech (TDS). The two groups were compared on forward recall of familiar words (pointing response), reverse recall of familiar words (pointing response), and reverse recall of digits (spoken response) and a receptive vocabulary task. There were no differences between children with TDS and children with PhDis on forward recall or vocabulary tasks. However, children with TDS significantly outperformed children with PhDis on the two reverse recall tasks. Findings suggest that atypical speech errors are associated with impaired phonological working memory, implicating executive function impairment in specific subtypes of SSD.     

Selective category and modality effects in deep dyslexia

We report a patient (FBI) in whom a category specific deep dyslexia was demonstrated. The patient was globally dysphasic with dyslexia and dysgraphia, and his dyslexic syndrome was characterised by a dramatic loss of phonological processing together with a partial loss of whole word reading. In the context of an overall poor level of reading accuracy, concrete words were read better than abstract words. Within this concrete word vocabulary, living items were read more accurately that non-living items. Perhaps most strikingly, he also had a remarkably preserved written proper noun vocabulary. A series of experiments explored the relationship between FBI's comprehension of the spoken and written word, and in each a significant category-by-modality interaction was demonstrated. His comprehension of the written word was impaired significantly more than his comprehension of the spoken word, but only for the impaired semantic category. This pattern of performance is interpreted as evidence for a degree of autonomy for the semantic processing of written words.     

Selective Category and Modality Effects in Deep Dyslexia

We report a patient (FBI) in whom a category specific deep dyslexia was demonstrated. The patient was globally dysphasic with dyslexia and dysgraphia, and his dyslexic syndrome was characterised by a dramatic loss of phonological processing together with a partial loss of whole word reading. In the context of an overall poor level of reading accuracy, concrete words were read better than abstract words. Within this concrete word vocabulary, living items were read more accurately that non-living items. Perhaps most strikingly, he also had a remarkably preserved written proper noun vocabulary. A series of experiments explored the relationship between FBI's comprehension of the spoken and written word, and in each a significant category-by-modality interaction was demonstrated. His comprehension of the written word was impaired significantly more than his comprehension of the spoken word, but only for the impaired semantic category. This pattern of performance is interpreted as evidence for a degree of autonomy for the semantic processing of written words.     

Alpha activity marking word boundaries mediates speech segmentation

This study examined the neurophysiological mechanisms of speech segmentation, the process of parsing the continuous speech signal into isolated words. Individuals listened to sequences of two monosyllabic words (e.g. gas source) and non‐words (e.g. nas sorf). When these phrases are spoken, talkers usually produce one continuous s‐sound, not two distinct s‐sounds, making it unclear where one word ends and the next one begins. This ambiguity in the signal can also result in perceptual ambiguity, causing the sequence to be heard as one word (failed to segment) or two words (segmented). We compared listeners' electroencephalogram activity when they reported hearing one word or two words, and found that bursts of fronto‐central alpha activity (9–14 Hz), following the onset of the physical /s/ and end of phrase, indexed speech segmentation. Left‐lateralized beta activity (14–18 Hz) following the end of phrase distinguished word from non‐word segmentation. A hallmark of enhanced alpha activity is that it reflects inhibition of task‐irrelevant neural populations. Thus, the current results suggest that disengagement of neural processes that become irrelevant as the words unfold marks word boundaries in continuous speech, leading to segmentation. Beta activity is likely associated with unifying word representations into coherent phrases.     

Successful single-word writing treatment: Experimental analyses of four cases

Background: Individuals with severe aphasia may fail to regain spoken language, so that treatment should target other communication modalities such as writing. There is relatively limited documentation of successful writing treatment, particularly in individuals with severe aphasia. Aims: The present study was designed to examine treatment outcomes in response to two writing treatment protocols intended to rebuild single-word vocabulary for written communication. Methods & Procedures: Writing treatments were implemented with four individuals who had significant aphasia and severe agraphia. Two participants received Anagram and Copy Treatment (ACT) which involved arrangement of component letters and repeated copying of target words, along with a homework programme called Copy and Recall Treatment (CART) that included copying and recall of target words. The other two participants received the homework-based CART only. Single-subject multiple-baseline designs were used with sets of words sequentially targeted for treatment. Outcomes & Results: All four participants responded positively to treatment. Three of the participants had severely limited spoken language, so that mastery of written words provided a much-needed means of communication. The fourth participant, who had adequate spoken language for face-to-face conversation, employed his improved spelling for written messages such as e-mail. Conclusions: Single-word writing abilities may improve with treatment despite long times post onset and persistent impairments to spoken language.     

The uses of overlap: Carer–child interaction involving a nine-year-old boy with auditory neuropathy

Abstract

The subject of this single case study, Ricky, is a nine-year-old boy with a profound hearing loss arising from auditory neuropathy. Despite cochlear implantation at the age of two, his receptive language skills remain very restricted and his speech is unintelligible. Techniques of interactional linguistics are used to analyse recordings of Ricky and his mother during shared book reading. Both participants display competences in managing turn-taking and overlapping talk that enable them to progress the book-reading activity, to talk spontaneously on topically related matters and also to handle issues of phonetic and linguistic repair. Instances of both competitive and non-competitive overlap reveal that Ricky has access to interactionally important prosodic skills. The study thus reinforces the need, when assessing a child’s potential to understand and use spoken language, to examine the child’s talk from an interactional perspective. It further indicates that overlapping talk is not necessarily a problem; indeed it can be part of a solution to issues of interpersonal understanding that routinely arise in the course of talk-in-interaction.     

Development of an audiovisual speech perception app for children with autism spectrum disorders

Perception of spoken language requires attention to acoustic as well as visible phonetic information. This article reviews the known differences in audiovisual speech perception in children with autism spectrum disorders (ASD) and specifies the need for interventions that address this construct. Elements of an audiovisual training program are described. This researcher-developed program delivered via an iPad app presents natural speech in the context of increasing noise, but supported with a speaking face. Children are cued to attend to visible articulatory information to assist in perception of the spoken words. Data from four children with ASD ages 8–10 are presented showing that the children improved their performance on an untrained auditory speech-in-noise task.     

Developmental dissociations between lexical reading and comprehension: Evidence from two cases of hyperlexia

We report two cases of developmental hyperlexia - JY and AD - who performed at normal levels or above in converting print into speech, but who were very impaired in spoken and written word comprehension. Our investigations focussed on whether these cases displayed evidence for normal acquisition of lexical reading skills, as indexed by unimpaired performance for age in reading aloud a set of irregular words, despite poor acquisition of semantic knowledge of the same words. In both cases, this dissociation was evident. The pattern of results was also demonstrated at an item level: the two cases showed no significant differences in reading accuracy for irregular words which they could define than for those which they could not. The results provide further evidence for the existence of a direct-lexical route from orthography to phonology, which is not necessarily mediated by semantic knowledge.     

Temporally selective attention supports speech processing in 3- to 5-year-old children

Recent event-related potential (ERP) evidence demonstrates that adults employ temporally selective attention to preferentially process the initial portions of words in continuous speech. Doing so is an effective listening strategy since word-initial segments are highly informative. Although the development of this process remains unexplored, directing attention to word onsets may be important for speech processing in young children who would otherwise be overwhelmed by the rapidly changing acoustic signals that constitute speech. We examined the use of temporally selective attention in 3- to 5-year-old children listening to stories by comparing ERPs elicited by attention probes presented at four acoustically matched times relative to word onsets: concurrently with a word onset, 100 ms before, 100 ms after, and at random control times. By 80 ms, probes presented at and after word onsets elicited a larger negativity than probes presented before word onsets or at control times. The latency and distribution of this effect is similar to temporally and spatially selective attention effects measured in adults and, despite differences in polarity, spatially selective attention effects measured in children. These results indicate that, like adults, preschool aged children modulate temporally selective attention to preferentially process the initial portions of words in continuous speech.     

Functionally relevant items in the treatment of aphasia (part I): Challenges for current practice

Background: Aphasiologists are motivated to select “functional”, “relevant” and “useful” items for use in therapy; yet the field lacks discussion on what is meant by these terms and how to identify such items.

Aims: The purpose of this article is to review the meaning of “functionally relevant” in the aphasia treatment literature and to specify challenges in identifying potentially relevant items for therapy.

Main Contribution: This article shows that aphasiologists lack clear definitions, strategies and concrete tools to assist with identification of functionally relevant items for language therapy. Two main categories of functional vocabulary are defined—personally chosen vocabulary and generally frequent vocabulary. The review of the existing aphasia literature demonstrates the strengths and weaknesses of these approaches. Two critical points are raised related to selection of therapy items using data from language corpora. Firstly, it is paradoxical that aphasiologists often try to target the most common vocabulary in therapy but that language corpora have not been used to determine the identity of the most frequent words. Secondly, the analyses of the language corpora show that the most frequent spoken words represent a wide variety of word classes, such as adjectives, adverbs and pronouns. Yet, only a few treatment studies have targeted words other than concrete nouns and verbs.

Conclusions: There is a need to use objective sources to identify and choose treatment targets. In addition, more therapy attempts should be directed to words other than the most concrete nouns and verbs. Use of frequency-based lists provides one way to identify and increase the number of items that are potentially relevant across people. Frequency-based vocabulary lists can also be used as a tool when asking people with aphasia or their significant others to identify items that they personally think should be targeted in therapy. Without creating and publishing common tools for this purpose, change in practice is difficult.     

Predictive Neural Computations Support Spoken Word Recognition: Evidence from MEG and Competitor Priming

Human listeners achieve quick and effortless speech comprehension through computations of conditional probability using Bayes rule. However, the neural implementation of Bayesian perceptual inference remains unclear. Competitive-selection accounts (e.g., TRACE) propose that word recognition is achieved through direct inhibitory connections between units representing candidate words that share segments (e.g., hygiene and hijack share /haidʒ/). Manipulations that increase lexical uncertainty should increase neural responses associated with word recognition when words cannot be uniquely identified. In contrast, predictive-selection accounts (e.g., Predictive-Coding) propose that spoken word recognition involves comparing heard and predicted speech sounds and using prediction error to update lexical representations. Increased lexical uncertainty in words, such as hygiene and hijack, will increase prediction error and hence neural activity only at later time points when different segments are predicted. We collected MEG data from male and female listeners to test these two Bayesian mechanisms and used a competitor priming manipulation to change the prior probability of specific words. Lexical decision responses showed delayed recognition of target words (hygiene) following presentation of a neighboring prime word (hijack) several minutes earlier. However, this effect was not observed with pseudoword primes (higent) or targets (hijure). Crucially, MEG responses in the STG showed greater neural responses for word-primed words after the point at which they were uniquely identified (after /haidʒ/ in hygiene) but not before while similar changes were again absent for pseudowords. These findings are consistent with accounts of spoken word recognition in which neural computations of prediction error play a central role.SIGNIFICANCE STATEMENT Effective speech perception is critical to daily life and involves computations that combine speech signals with prior knowledge of spoken words (i.e., Bayesian perceptual inference). This study specifies the neural mechanisms that support spoken word recognition by testing two distinct implementations of Bayes perceptual inference. Most established theories propose direct competition between lexical units such that inhibition of irrelevant candidates leads to selection of critical words. Our results instead support predictive-selection theories (e.g., Predictive-Coding): by comparing heard and predicted speech sounds, neural computations of prediction error can help listeners continuously update lexical probabilities, allowing for more rapid word identification.     

Predictability affects early perceptual processing of word onsets in continuous speech

Event-related potential (ERP) evidence indicates that listeners selectively attend to word onsets in continuous speech, but the reason for this preferential processing is unknown. The current study measured ERPs elicited by syllable onsets in an artificial language to test the hypothesis that listeners direct attention to word onsets because their identity is unpredictable. Both before and after recognition training, participants listened to a continuous stream of six nonsense words arranged in pairs, such that the second word in each pair was completely predictable. After training, first words in pairs elicited a larger negativity beginning around 100 ms after onset. This effect was not evident for the completely predictable second words in pairs. These results suggest that listeners are most likely to attend to the segments in speech that they are least able to predict.     

Using our current understanding of dyslexia to support early identification and intervention

One of the major risk factors for reading disability is difficulty learning to read words in text in an accurate and fluent manner. This is apparent when a child at risk of dyslexia first starts to attempt to read. Dyslexic children struggle to grasp and automate the alphabetic principle (ie, they cannot "sound out" words or use phonemic decoding strategies) and therefore have difficulty deciphering unfamiliar words that they have not encountered before. Even though many of these words are part of the child's oral vocabulary, the child cannot recognize them in printed form. As a result, reading can be extremely laborious and time-consuming, fraught with errors, and altogether an unrewarding, aversive experience. To be an efficient reader, one must be able to rapidly and effortlessly recognize many words by sight, and for a child to acquire this facility requires multiple exposures to these words. The difficulty that dyslexic children have in developing reliable and efficient phonemic decoding ability makes the acquisition of a lexicon of sight words a much slower process than it is for the average reader. Several other factors can affect a child's ability to read, which are reviewed herein. However, early recognition and treatment of deficient phonologic awareness are an extremely important step in the prevention of a reading problem in the child who is at risk of dyslexia.     

Attention to language: Novel MEG paradigm for registering involuntary language processing in the brain

Previous research indicates that, under explicit instructions to listen to spoken stimuli or in speech-oriented behavioural tasks, the brain's responses to senseless pseudowords are larger than those to meaningful words; the reverse is true in non-attended conditions. These differential responses could be used as a tool to trace linguistic processes in the brain and their interaction with attention. However, as previous studies relied on explicit instructions to attend or ignore the stimuli, a technique for automatic attention modulation (i.e., not dependent on explicit instruction) would be more advantageous, especially when cooperation with instructions may not be guaranteed (e.g., neurological patients, children etc). Here we present a novel paradigm in which the stimulus context automatically draws attention to speech. In a non-attend passive auditory oddball sequence, rare words and pseudowords were presented among frequent non-speech tones of variable frequency and length. The low percentage of spoken stimuli guarantees an involuntary attention switch to them. The speech stimuli, in turn, could be disambiguated as words or pseudowords only in their end, at the last phoneme, after the attention switch would have already occurred. Our results confirmed that this paradigm can indeed be used to induce automatic shifts of attention to spoken input. At ～250ms after the stimulus onset, a P3a-like neuromagnetic deflection was registered to spoken (but not tone) stimuli indicating an involuntary attention shift. Later, after the word-pseudoword divergence point, we found a larger oddball response to pseudowords than words, best explained by neural processes of lexical search facilitated through increased attention. Furthermore, we demonstrate a breakdown of this orderly pattern of neurocognitive processes as a result of sleep deprivation. The new paradigm may thus be an efficient way to assess language comprehension processes and their dynamic interaction with those of attention allocation. It does it in an automatic and task-free fashion, indicating its potential benefit for assessing uncooperative clinical populations.     

Speech development test for one-year-old infants: I. Test content]

A new speech development test was prepared for one-year-old infants. The test consists of three parts: test I, II, and III. The overall test originally comprised a total of 98 test items (47 for Test I, 32 for Test II and 19 for Test III). Test I (for pre-speech language) Section 1 Situation of language i) Differentiation of information to be communicated ii) Comprehension of speech-related situation (Initiation of "signe", and comprehension of objects and events by means of speech) Section 2 Development of symbolizing function (Development and transformation of ability to handle and manipulate objects) section 3 Representing the function of language (First utterance, and acquisition of meaningful words after first utterance) Test II (for speech comprehension) Ability to name concrete objects, and to relate objects to their uses and functions; comprehension of words representing spatial concept such as quantity, number and dimensions, as well as words representing color or position. Test III (for speech expression) Ability to verbalize or name concrete objects, and to verbalize the conduct and state of a person. For infants, language is an objective to be achieved, while for adults it is the mean of thinking and communicating. Despite this difference the scope of this test comprises two major aspects common to the language-related experience of infants and of adults: pragmatics and vocabulary.     

Neural bases of talker normalization

To recognize phonemes across variation in talkers, listeners can use information about vocal characteristics, a process referred to as "talker normalization." The present study investigates the cortical mechanisms underlying talker normalization using fMRI. Listeners recognized target words presented in either a spoken list produced by a single talker or a mix of different talkers. It was found that both conditions activate an extensive cortical network. However, recognizing words in the mixed-talker condition, relative to the blocked-talker condition, activated middle/superior temporal and superior parietal regions to a greater degree. This temporal-parietal network is possibly associated with selectively attending and processing spectral and spatial acoustic cues required in recognizing speech in a mixed-talker condition.