Phonological Neighborhood Density Research Articles

The Cerebellum Is Sensitive to the Lexical Properties of Words During Spoken Language Comprehension

Abstract Over the past few decades, research into the function of the cerebellum has expanded far beyond the motor domain. A growing number of studies are probing the role of specific cerebellar subregions, such as Crus I and Crus II, in higher-order cognitive functions including receptive language processing. In the current fMRI study, we show evidence for the cerebellum’s sensitivity to variation in two well-studied psycholinguistic properties of words—lexical frequency and phonological neighborhood density—during passive, continuous listening of a podcast. To determine whether, and how, activity in the cerebellum correlates with these lexical properties, we modeled each word separately using an amplitude-modulated regressor, time-locked to the onset of each word. At the group level, significant effects of both lexical properties landed in expected cerebellar subregions: Crus I and Crus II. The BOLD signal correlated with variation in each lexical property, consistent with both language-specific and domain-general mechanisms. Activation patterns at the individual level also showed that effects of phonological neighborhood and lexical frequency landed in Crus I and Crus II as the most probable sites, though there was activation seen in other lobules (especially for frequency). Although the exact cerebellar mechanisms used during speech and language processing are not yet evident, these findings highlight the cerebellum’s role in word-level processing during continuous listening.

Inhibitory and facilitative effects of lexical neighbors in spoken word recognition: The role of language experience

AbstractThe study evaluated whether the direction (inhibitory or facilitative) of the phonological neighborhood density effect in English spoken word recognition was modulated by the relative strength of competitor activation (neighborhood type) in two groups of English-dominant learners of Spanish who differed in language experience. Classroom learners and heritage learners of Spanish identified spoken English words from dense (e.g., BEAR) and sparse (e.g., BOAT) phonological neighborhoods presented in moderate noise. The phonological neighborhood was separately manipulated at word onset (cohort) and word offset (rhyme). Classroom learners were overall slower in recognizing spoken words from denser neighborhoods. Strongly active (onset) neighbors exerted inhibitory effects in both classroom and heritage learners. Critically, weakly active (offset) neighbors exerted inhibitory effects in classroom learners but facilitative effects in heritage learners. The results suggest that the activation of both within and cross-language neighbors should be considered in determining the direction of neighbor effects in bilingual lexical processing.

Neurophysiological effects of frequency, length, phonological neighborhood density, and iconicity on sign recognition.

Current theories on lexical recognition are mostly based on studies from spoken languages or their written forms. Much less is known about the process of lexical recognition in sign languages. This study aims to examine the neural correlates of sign recognition by investigating the effects of lexical frequency, length, phonological neighborhood density, and iconicity during Chinese Sign Language comprehension. Twenty-two deaf signers viewed a set of sign videos that varied in the 4 lexical properties and decided if they referred to animals, while event-related potential responses were recorded. Data were analyzed through linear mixed-effects models with the lexical variables treated as continuous measures. The results showed that frequency modulated ERP amplitude as early as around 200 ms and in the late N400 time frame. Sign length invoked effects throughout the process, starting from 200 ms and pertaining to the last epoch. Neighborhood density effects were also observed early around 200 ms and later on the N400 and late positive complex (LPC). Iconicity produced robust effects on the N400 and LPC amplitude. Lexical frequency, length, and neighborhood density influence the neural dynamics of sign recognition in a similar way as to spoken words. Iconicity can confer a processing advantage due to closer form-meaning mappings. The results indicate that lexical recognition engages some mechanisms that are universal across the signed and spoken modality, but it can also be regulated by modality-specific properties such as the prevalent iconicity in sign languages.

Correlates of word likeness in the perception of pseudowords

New words are often introduced into languages from borrowings or neologisms. Pseudowords (possible words of a language that have not yet been assigned meaning) are used in many experiments to test aspects of speech perception. However, what we know about the perception of pseudowords is relatively limited. In this study, we investigate word likeness ratings of pseudowords on a 1–7 scale. A total of 659 listeners responded to sets of 200 pseudowords from an item list of 9599 English-sounding pseudowords varying in number of syllables and morphological complexity. We analyze the listeners' responses with the following predictors: phonotactic predictability, duration, phonological neighborhood density, phonological uniqueness point, pseudo morphological complexity, and acoustic distinctiveness. We analyze the ordinal data to identify how these predictors influence listeners’ ratings. We also take average word likeness ratings of the pseudowords and use them to predict a different set of listeners’ reaction times in a lexical decision task. In this presentation, we discuss what properties of the pseudowords influence what makes them seem more word-like or not and how word-likeness affects auditory word recognition.

Investigating the effects of phonological neighborhood density, word frequency, and phoneme confusability on the English word recognition by native speakers of Japanese

This study aims to bridge the gap between previous research on the impact of phonological neighborhood density on word identification, which did not consider phoneme confusability, and studies on phoneme identification and discrimination, which did not account for the effects of phonological neighborhood density. Native Japanese listeners participated in this study, where they were tasked with identifying monosyllabic and disyllabic English words. The words varied in both phonological neighborhood density and word frequency and were produced by native speakers of American English and Japanese. Participants responded by typing the words they heard. The findings of this study indicated that there were no significant effects of phonological neighborhood density on word identification. However, frequent words were identified with greater accuracy compared to infrequent words. Moreover, words produced by native speakers of American English were more accurately identified than those produced by Japanese speakers. Japanese listeners' inaccurate perception of phonemes has resulted in word identification errors in both dense and sparse phonological neighborhoods. For example, they often mistakenly identify /l/ as /r/ and vice versa. Low and central vowels /æ, ɑ, ʌ/ are frequently misidentified as one another. These confusions are commonly observed among Japanese learners of English.

Multilevel factors predict treatment response following semantic feature-based intervention in bilingual aphasia.

Semantic feature-based treatments (SFTs) are effective rehabilitation strategies for word retrieval deficits in bilinguals with aphasia (BWA). However, few studies have prospectively evaluated the effects of key parameters of these interventions on treatment outcomes. This study examined the influence of intervention-level (i.e., treatment language and treatment sessions), individual-level (baseline naming severity and age), and stimulus-level (i.e., lexical frequency, phonological length, and phonological neighborhood density) factors on naming improvement in a treated and untreated language for 34 Spanish-English BWA who completed 40 hours of SFT. Results revealed significant improvement over time in both languages. In the treated language, individuals who received therapy in their L1 improved more. Additionally, higher pre-treatment naming scores predicted greater response to treatment. Finally, a frequency effect on baseline naming accuracy and phonological effects on accuracy over time were associated with differential treatment gains. These findings indicate that multilevel factors are influential predictors of bilingual treatment outcomes.

Parallel or sequential? Decoding conceptual and phonological/phonetic information from MEG signals during language production

ABSTRACT Speaking requires the temporally coordinated planning of core linguistic information, from conceptual meaning to articulation. Recent neurophysiological results suggested that these operations involve a cascade of neural events with subsequent onset times, whilst competing evidence suggests early parallel neural activation. To test these hypotheses, we examined the sources of neuromagnetic activity recorded from 34 participants overtly naming 134 images from 4 object categories (animals, tools, foods and clothes). Within each category, word length and phonological neighbourhood density were co-varied to target phonological/phonetic processes. Multivariate pattern analyses (MVPA) searchlights in source space decoded object categories in occipitotemporal and middle temporal cortex, and phonological/phonetic variables in left inferior frontal (BA 44) and motor cortex early on. The findings suggest early activation of multiple variables due to intercorrelated properties and interactivity of processing, thus raising important questions about the representational properties of target words during the preparatory time enabling overt speaking.

Predicting Confrontation Naming in the Logopenic Variant of Primary Progressive Aphasia

ABSTRACT Background Naming difficulties are prominent and pervasive in the logopenic variant of primary progressive aphasia (lvPPA) and may reflect its underlying deficits in phonological processing. Importantly, some words appear to be more vulnerable to deterioration than others. We hypothesize that these differences can be explained, in part, by the unique psycholinguistic properties of words. Aims Our study investigated the role of psycholinguistic properties of words, along with their underlying psycholinguistic factors, in predicting confrontation naming performance in individuals with lvPPA. Methods & Procedures Naming accuracy data were collected from 14 individuals with lvPPA using the Boston Naming Test (BNT). For each test item, values were extracted for frequency, age of acquisition (AoA), familiarity, word length, phonological neighborhood density (PND), semantic neighborhood density (SND), arousal, and valence. We examined the effects of these psycholinguistic properties on naming accuracy using logistic regression analyses at the individual level and multiple linear regression analysis at the group level. Further, we performed mediation analyses to examine the mediating contributions of related psycholinguistic properties on naming accuracy. Finally, principal component analysis (PCA) was performed to extract fundamental factors of the psycholinguistic properties. These factor scores were entered into regression analyses to investigate their relative contribution to naming accuracy in lvPPA. Outcomes & Results Age of acquisition emerged as the strongest psycholinguistic predictor of naming accuracy in lvPPA at both the individual and group levels. The influence of AoA on naming accuracy was only partially mediated by frequency. Three principal psycholinguistic factors were extracted from the PCA. These were interpreted as “lexical-semantic usage”, “phonological complexity”, and “emotional intensity”. Results indicated that “lexical-semantic usage” and “emotional intensity” predicted naming performance at both the individual and group levels. Conclusions Age of acquisition has been associated with the phonological level in models of word naming. The observed psycholinguistic effects on naming accuracy are discussed in the context of phonological deficits in lvPPA and models of word naming.

Second dialect acquisition and phonetic vowel reduction in the American Midwest

Geographic mobility can lead to the acquisition of new regional dialect features. This second dialect acquisition is highly variable across individuals and is affected by a range of linguistic and social factors. The realization of dialect-specific features is also affected by linguistic variables related to phonetic reduction, but this interaction has been primarily examined with a mix of mobile and non-mobile participants. In the current study, second dialect acquisition by Midwestern American young adults and its interaction with phonetic reduction processes was examined. Relative to lifetime residents of the Northern and Midland regions of American English, some Northern transplants to the Midland region exhibited second dialect acquisition and others exhibited maintenance of Northern dialect features. All talkers showed phonetic reduction due to lexical frequency, phonological neighborhood density, discourse mention, semantic predictability, and speaking style. These phonetic reduction processes only weakly interacted with dialect variation, such that less phonetic reduction was observed overall when it was potentially in conflict with dialect-specific vowel features. Taken together, the results provide additional evidence for substantial individual variation in second dialect acquisition, but limited evidence of an effect of second dialect acquisition on the interaction between dialect variation and phonetic reduction processes.

Do age and language impairment affect speed of recognition for words with high and low closeness centrality within the phonological network?

Purpose Speed and accuracy of lexical access change with healthy ageing and neurodegeneration. While a word's immediate phonological neighbourhood density (i.e. words differing by a single phoneme) influences access, connectivity to all words in the phonological network (i.e. closeness centrality) may influence processing. This study aimed to investigate the effect of closeness centrality on speed and accuracy of lexical processing pre- and post- a single word-training session in healthy younger and older adults, and adults with logopenic primary progressive aphasia (lvPPA), which affects phonological processing. Method Participants included 29 young and 17 older healthy controls, and 10 adults with lvPPA. Participants received one session of word-training on words with high or low closeness centrality, using a picture-word verification task. Changes in lexical decision reaction times (RT) and accuracy were measured. Result Baseline RT was unaffected by age and accuracy was at ceiling for controls. Post-training, only young adults' RT were significantly faster. Adults with lvPPA were slower and less accurate than controls at baseline, with no training effect. Closeness centrality did not influence performance. Conclusion Absence of training effect for older adults suggests higher threshold to induce priming, possibly associated with insufficient dosage or fatigue. Implications for word-finding interventions with older adults are discussed.

Multilingual spoken word recognition: A megastudy approach

Bilingualism research has primarily focused on the perception and processing of individual sounds or word learning. Many studies have investigated how bilingual listeners perceive sound contrasts that don't create lexical distinctions in their native language. There is substantially less research that has investigated how word-level properties impact L2 auditory processing. The present study examines how auditory lexical processing differs between monolingual and bilingual listeners with different language backgrounds. We collected lexical decision accuracies and latencies for 26,793 words and 9600 pseudowords from the Massive Auditory Lexical Decision database from native and non-native listener responses. We compare the language backgrounds of our 1028 listeners and group them into four groups: native speakers, early, early-late, and late bilinguals. We report the findings of an analysis investigating how language background and proficiency modulate lexical effects to understand how language background influences spoken word recognition. We find differences in the effects of lexical frequency, phonological neighborhood density, and phonological uniqueness point between the different listener groups. We discuss the impact of bilingualism in a word recognition task and how these results inform models of spoken word recognition and second language acquisition.

Noise Modulates Crosslinguistic Effects on Second-Language Auditory Word Recognition.

This study investigates whether crosslinguistic effects on auditory word recognition are modulated by the quality of the auditory signal (clear and noisy). In an online experiment, a group of Spanish-English bilingual listeners performed an auditory lexical decision task, in their second language, English. Words and pseudowords were either presented in the clear or were embedded in white auditory noise. Target words were varied in the degree to which they overlapped in their phonological form with their translation equivalents and were categorized according to their overlap as cognates (form and meaning) or noncognates (meaning only). In order to test for effects of crosslinguistic competition, the phonological neighborhood density of the targets' translations was also manipulated. The results show that crosslinguistic effects are impacted by noise; when the translation had a high neighborhood density, performance was worse for cognates than for noncognates, especially in noise. The findings suggest that noise increases lexical competition across languages, as it does within a language, and that the crosslinguistic phonological overlap for cognates compared with noncognates can further increase the pool of competitors by co-activating crosslinguistic lexical candidates. The results are discussed within the context of the bilingual word recognition literature and models of language and bilingual lexical processing.

Diffusion of Phonetic Updates within Phonological Neighborhoods

Phonological neighborhood density is known to influence lexical access, speech production and perception processes. Lexical competition is considered the central concept from which the neighborhood effect emanates: highly competitive neighborhoods are characterized by large degrees of phonemic co-activation, which can delay speech recognition and facilitate speech production. The study investigates phonetic learning in English as a foreign language in relation to phonological neighborhood density and onset density to see if dense or sparse neighborhoods are more conducive to the incorporation of novel phonetic detail. Also, the effect of voice-contrasted minimal pairs is explored. The results indicate that sparser neighborhoods with weaker lexical competition provide the most optimal phonological environment for phonetic learning. Moreover, novel phonetic details are incorporated faster in neighborhoods without minimal pairs. The results indicate that lexical competition plays a role in the dissemination of phonetic updates in the lexicon of foreign language learners.

Relative Contributions of Social, Contextual, and Lexical Factors in Speech Processing.

This exploratory study examined the simultaneous interactions and relative contributions of bottom-up social information (regional dialect, speaking style), top-down contextual information (semantic predictability), and the internal dynamics of the lexicon (neighborhood density, lexical frequency) to lexical access and word recognition. Cross-modal matching and intelligibility in noise tasks were conducted with a community sample of adults at a local science museum. Each task featured one condition in which keywords were presented in isolation and one condition in which they were presented within a multiword phrase. Lexical processing was slower and more accurate when keywords were presented in their phrasal context, and was both faster and more accurate for auditory stimuli produced in the local Midland dialect. In both tasks, interactions were observed among stimulus dialect, speaking style, semantic predictability, phonological neighborhood density, and lexical frequency. These interactions revealed that bottom-up social information and top-down contextual information contribute more to speech processing than the internal dynamics of the lexicon. Moreover, the relatively stronger bottom-up social effects were observed in both the isolated word and multiword phrase conditions, suggesting that social variation is central to speech processing, even in non-interactive laboratory tasks. At the same time, the specific interactions observed differed between the two experiments, reflecting task-specific demands related to processing time constraints and signal degradation.

The Time Course of Language Production as Revealed by Pattern Classification of MEG Sensor Data.

Language production involves a complex set of computations, from conceptualization to articulation, which are thought to engage cascading neural events in the language network. However, recent neuromagnetic evidence suggests simultaneous meaning-to-speech mapping in picture naming tasks, as indexed by early parallel activation of frontotemporal regions to lexical semantic, phonological, and articulatory information. Here we investigate the time course of word production, asking to what extent such “earliness” is a distinctive property of the associated spatiotemporal dynamics. Using MEG, we recorded the neural signals of 34 human subjects (26 males) overtly naming 134 images from four semantic object categories (animals, foods, tools, clothes). Within each category, we covaried word length, as quantified by the number of syllables contained in a word, and phonological neighborhood density to target lexical and post-lexical phonological/phonetic processes. Multivariate pattern analyses searchlights in sensor space distinguished the stimulus-locked spatiotemporal responses to object categories early on, from 150 to 250 ms after picture onset, whereas word length was decoded in left frontotemporal sensors at 250-350 ms, followed by the latency of phonological neighborhood density (350-450 ms). Our results suggest a progression of neural activity from posterior to anterior language regions for the semantic and phonological/phonetic computations preparing overt speech, thus supporting serial cascading models of word production.SIGNIFICANCE STATEMENT Current psycholinguistic models make divergent predictions on how a preverbal message is mapped onto articulatory output during the language planning. Serial models predict a cascading sequence of hierarchically organized neural computations from conceptualization to articulation. In contrast, parallel models posit early simultaneous activation of multiple conceptual, phonological, and articulatory information in the language system. Here we asked whether such earliness is a distinctive property of the neural dynamics of word production. The combination of the millisecond precision of MEG with multivariate pattern analyses revealed subsequent onset times for the neural events supporting semantic and phonological/phonetic operations, progressing from posterior occipitotemporal to frontal sensor areas. The findings bring new insights for refining current theories of language production.

The recognition of spoken pseudowords

ABSTRACT Pseudowords are used as stimuli in many psycholinguistic experiments, yet they remain largely under-researched. To better understand the cognitive processing of pseudowords, we analysed the pseudoword responses in the Massive Auditory Lexical Decision megastudy data set. Linguistic characteristics that influence the processing of real English words – namely, phonotactic probability, phonological neighbourhood density, uniqueness point, and morphological complexity – were also found to influence the processing time of spoken pseudowords. Subsequently, we analysed how the linguistic characteristics of non-unique portions of pseudowords influenced processing time. We again found that the named linguistic characteristics affected processing time, highlighting the dynamicity of activation and competition. We argue these findings also speak to learning new words and spoken word recognition generally. We then discuss what aspects of pseudoword recognition a full model of spoken word recognition must account for. We finish with a re-description of the auditory lexical decision task in light of our results.

The differential roles of lexical and sublexical processing during spoken-word recognition in clear and in noise

Successful spoken-word recognition relies on interplay between lexical and sublexical processing. Previous research demonstrated that listeners readily shift between more lexically-biased and more sublexically-biased modes of processing in response to the situational context in which language comprehension takes place. Recognizing words in the presence of background noise reduces the perceptual evidence for the speech signal and – compared to the clear – results in greater uncertainty. It has been proposed that, when dealing with greater uncertainty, listeners rely more strongly on sublexical processing. The present study tested this proposal using behavioral and electroencephalography (EEG) measures. We reasoned that such an adjustment would be reflected in changes in the effects of variables predicting recognition performance with loci at lexical and sublexical levels, respectively. We presented native speakers of Dutch with words featuring substantial variability in (1) word frequency (locus at lexical level), (2) phonological neighborhood density (loci at lexical and sublexical levels) and (3) phonotactic probability (locus at sublexical level). Each participant heard each word in noise (presented at one of three signal-to-noise ratios) and in the clear and performed a two-stage lexical decision and transcription task while EEG was recorded. Using linear mixed-effects analyses, we observed behavioral evidence that listeners relied more strongly on sublexical processing when speech quality decreased. Mixed-effects modelling of the EEG signal in the clear condition showed that sublexical effects were reflected in early modulations of ERP components (e.g., within the first 300 msec post word onset). In noise, EEG effects occurred later and involved multiple regions activated in parallel. Taken together, we found evidence – especially in the behavioral data – supporting previous accounts that the presence of background noise induces a stronger reliance on sublexical processing.

Using acoustic distance and acoustic absement to quantify lexical competition

Using phonological neighborhood density has been a common method to quantify lexical competition. It is useful and convenient but has shortcomings that are worth reconsidering. The present study quantifies the effects of lexical competition during spoken word recognition using acoustic distance and acoustic absement rather than phonological neighborhood density. The indication of a word's lexical competition is given by what is termed to be its acoustic distinctiveness, which is taken as its average acoustic absement to all words in the lexicon. A variety of acoustic representations for items in the lexicon are analyzed. Statistical modeling shows that acoustic distinctiveness has a similar effect trend as that of phonological neighborhood density. Additionally, acoustic distinctiveness consistently increases model fitness more than phonological neighborhood density regardless of which kind of acoustic representation is used. However, acoustic distinctiveness does not seem to explain all of the same things as phonological neighborhood density. The different areas that these two predictors explain are discussed in addition to the potential theoretical implications of the usefulness of acoustic distinctiveness in the models. The present paper concludes with some reasons why a researcher may want to use acoustic distinctiveness over phonological neighborhood density in future experiments.

A web-based interface to calculate phonological neighborhood density for words and nonwords in Modern Standard Arabic

The availability of online databases (e.g., Balota et al., 2007) and calculators (e.g., Storkel & Hoover, 2010) has contributed to an increase in psycholinguistic-related research, to the development of evidence-based treatments in clinical settings, and to scientifically supported training programs in the language classroom. The benefit of online language resources is limited by the fact that the majority of such resources provide information only for the English language (Vitevitch, Chan & Goldstein, 2014). To address the lack of diversity in these resources for languages that differ phonologically and morphologically from English, the present article describes an online database to compute phonological neighborhood density (i.e., the number of words that sound similar to a given word) for words and nonwords in Modern Standard Arabic (MSA). A full description of how the calculator can be used is provided. It can be freely accessed at https://calculator.ku.edu/density/about.

Out of sight, out of mind: The influence of communicative load and phonological neighborhood density on phonetic variation in real listener-directed speech.

Some models of speech production propose that speech variation reflects an adaptive trade-off between the needs of the listener and constraints on the speaker. The current study considers communicative load as both a situational and lexical variable that influences phonetic variation in speech to real interlocutors. The current study investigates whether the presence or absence of a target word in the sight of a real listener influences speakers' patterns of variation during a communicative task. To test how lexical difficulty also modulates intelligibility, target words varied in phonological neighborhood density (ND), a measure of lexical difficulty. Acoustic analyses reveal that speakers produced longer vowels in words that were not visually present for the listener to see, compared to when the listener could see those words. This suggests that speakers assess in real time the presence or absence of supportive visual information in assessing listener comprehension difficulty. Furthermore, the presence or absence of the word interacted with ND to predict both vowel duration and hyperarticulation patterns. These findings indicate that lexical measures of a word's difficulty and speakers' online assessment of lexical intelligibility (based on a word's visual presence or not) interactively influence phonetic modifications during communication with a real listener.