A Web-based interface to calculate phonotactic probability for words and nonwords in English

Phonotactic probability refers to the frequency with which phonological segments and sequences of phonological segments occur in words in a given language. We describe one method of estimating phonotactic probabilities based on words in American English. These estimates of phonotactic probability have been used in a number of previous studies and are now being made available to other researchers via a Web-based interface. Instructions for using the interface, as well as details regarding how the measures were derived, are provided in the present article. The Phonotactic Probability Calculator can be accessed athttp://www.people.ku.edu/~mvitevit/PhonoProbHome.html.     

Effects of Vocabulary and Phonotactic Probability on 2-Year-Olds’ Nonword Repetition

This study investigates the relationship between nonword repetition (NWR) and vocabulary in 2-year-olds. Questions addressed are whether (1) NWR and vocabulary are associated, (2) phonotactic probability affects NWR, and (3) there is an interaction effect between phonotactic probability and vocabulary on NWR performance. The general aim of the study is to investigate whether NWR, as a task of phonological storage, assesses the quality of phonological representations in children as young as 2 years of age. 557 Dutch 2-year-olds performed a NWR task containing items of varying phonotactic probability as well as a receptive vocabulary task. The results showed a moderate, significant correlation between NWR and vocabulary. Phonotactic probability had an effect on NWR performance. Further analyses showed that there was a significant interaction between phonotactic probability and vocabulary for part of the items. These results support previously reported effects of vocabulary and phonotactic probability on NWR in older, English-speaking children for a large sample of Dutch-speaking 2-year-olds, and provide evidence that NWR assesses the quality of phonological representations already in very young children.     

Sublexical and lexical representations in speech production: effects of phonotactic probability and onset density

Phonotactic probability, neighborhood density, and onset density were manipulated in 4 picture-naming tasks. Experiment 1 showed that pictures of words with high phonotactic probability were named more quickly than pictures of words with low phonotactic probability. This effect was consistent over multiple presentations of the pictures (Experiment 2). Manipulations of phonotactic probability and neighborhood density showed only an influence of phonotactic probability (Experiment 3). In Experiment 4, pictures of words with sparse onsets were named more quickly than pictures of words with dense onsets. The results of these experiments provide additional constraints on the architecture and processes involved in models of speech production, as well as constraints on the connections between the recognition and production systems.     

Phonotactic and Prosodic Effects on Word Segmentation in Infants

This research examines the issue of speech segmentation in 9-month-old infants. Two cues known to carry probabilistic information about word boundaries were investigated: Phonotactic regularity and prosodic pattern. The stimuli used in four head turn preference experiments were bisyllabic CVC.CVC nonwords bearing primary stress in either the first or the second syllable (strong/weak vs. weak/strong). Stimuli also differed with respect to the phonotactic nature of their cross-syllabic C.C cluster. Clusters had either a low probability of occurring at a word juncture in fluent speech and a high probability of occurring inside of words ("within-word" clusters) or a high probability of occurring at a word juncture and a low probability of occurring inside of words ("between-word" clusters). Our results show that (1) 9-month-olds are sensitive to how phonotactic sequences typically align with word boundaries, (2) altering the stress pattern of the stimuli reverses infants' preference for phonotactic cluster types, (3) the prosodic cue to segmentation is more strongly relied upon than the phonotactic cue, and (4) a preference for high-probability between-word phonotactic sequences can be obtained either by placing stress on the second syllable of the stimuli or by inserting a pause between syllables. The implications of these results are discussed in light of an integrated multiple-cue approach to speech segmentation in infancy.     

An online calculator to compute phonotactic probability and neighborhood density on the basis of child corpora of spoken American English

An online calculator was developed (www.bncdnet.ku.edu/cml/info_ccc.vi) to compute phonotactic probability—the likelihood of occurrence of a sound sequence—and neighborhood density—the number of phonologically similar words—on the basis of child corpora of American English (Kolson, 1960; Moe, Hopkins, & Rush, 1982) and to compare its results to those of an adult calculator. Phonotactic probability and neighborhood density were computed for a set of 380 nouns (Fenson et al., 1993) using both the child and adult corpora. The child and adult raw values were significantly correlated. However, significant differences were detected. Specifically, child phonotactic probability was higher than adult phonotactic probability, especially for highprobability words, and child neighborhood density was lower than adult neighborhood density, especially for words with high-density neighborhoods. These differences were reduced or eliminated when relative measures (i.e., z scores) were used. Suggestions are offered regarding which values to use in future research.     

A neuronal model for syllable representation

A speculative neuronal template, equivalent to canonical syllable forms and independent of segmental representations, is offered to help account for (1) the inviolate nature of phonotactic constraints in aphasic speech output, and (2) left hemisphere specialization for speech sound access and output. The model, which attempts to relate plausible neuronal systems to linguistic function, is based on cell assemblies that are thought to develop by way of genetic predisposition and ontogenetic language experience, into configurations that can represent canonical slot positions for the consonants and vowel comprising a syllable. The syllable is assumed to be the basic organizational rhythmic unit for serial concatenation of sublexical segments. A scheme for neurological differentiation of vowels and consonants is offered. Phonotactic constraints can become "hard-wired" to help create the automaticity underlying phonological sound organization. Testable predictions are offered to substantiate the claims of the model.     

Phonotactics, neighborhood activation, and lexical access for spoken words.

Probabilistic phonotactics refers to the relative frequencies of segments and sequences of segments in spoken words. Neighborhood density refers to the number of words that are phonologically similar to a given word. Despite a positive correlation between phonotactic probability and neighborhood density, nonsense words with high probability segments and sequences are responded to more quickly than nonsense words with low probability segments and sequences, whereas real words occurring in dense similarity neighborhoods are responded to more slowly than real words occurring in sparse similarity neighborhoods. This contradiction may be resolved by hypothesizing that effects of probabilistic phonotactics have a sublexical focus and that effects of similarity neighborhood density have a lexical focus. The implications of this hypothesis for models of spoken word recognition are discussed.     

Phonotactic probability of brand names: I'd buy that!

Psycholinguistic research shows that word-characteristics influence the speed and accuracy of various language-related processes. Analogous characteristics of brand names influence the retrieval of product information and the perception of risks associated with that product. In the present experiment we examined how phonotactic probability-the frequency with which phonological segments and sequences of segments appear in a word-might influence consumer behavior. Participants rated brand names that varied in phonotactic probability on the likelihood that they would buy the product. Participants indicated that they were more likely to purchase a product if the brand name was comprised of common segments and sequences of segments rather than less common segments and sequences of segments. This result suggests that word-characteristics may influence higher-level cognitive processes, in addition to language-related processes. Furthermore, the benefits of using objective measures of word characteristics in the design of brand names are discussed.     

A corpus of consonant–vowel–consonant real words and nonwords: Comparison of phonotactic probability, neighborhood density, and consonant age of acquisition

A corpus of 5,765 consonant–vowel–consonant sequences (CVCs) was compiled, and phonotactic probability and neighborhood density were computed for both child and adult corpora. This corpus of CVCs, provided as supplementary materials, was analyzed to address the following questions: (1) Do computations based on a child corpus differ from those based on an adult corpus? (2) Do the phonotactic probability and/or the neighborhood density of real words differ from those of nonwords? (3) Do phonotactic probability and/or neighborhood density differ across CVCs that vary in consonant age of acquisition? The results showed significant differences in phonotactic probability and neighborhood density for the child versus adult corpora, replicating prior findings. The impact of this difference on future studies will depend on the level of precision needed when specifying probability and density. In addition, significant and large differences in phonotactic probability and neighborhood density were detected between real words and nonwords, which may present methodological challenges for future research. Finally, CVCs composed of earlier-acquired sounds differed significantly in probability and density from those composed of later-acquired sounds, although this effect was relatively small and is less likely to present significant methodological challenges to future studies.     

Early effects of neighborhood density and phonotactic probability of spoken words on event-related potentials

All current models of spoken word recognition propose that sound-based representations of spoken words compete with, or inhibit, one another during recognition. In addition, certain models propose that higher probability sublexical units facilitate recognition under certain circumstances. Two experiments were conducted examining ERPs to spoken words and nonwords simultaneously varying in phonotactic probability and neighborhood density. Results showed that the amplitude of the P2 potential was greater for high probability-density words and nonwords, suggesting an early inhibitory effect of neighborhood density. In order to closely examine the role of phonotactic probability, effects of initial phoneme frequency were also examined. The latency of the P2 potential was shorter for words with high initial-consonant probability, suggesting a facilitative effect of phonotactic probability. The current results are consistent with findings from previous studies using reaction time and eye-tracking paradigms and provide new insights into the time-course of lexical and sublexical activation and competition.     

Modulation of brain activity during phonological familiarization

We measured brain activity in 12 adults for the repetition of auditorily presented words and nonwords, before and after repeated exposure to their phonological form. The nonword phoneme combinations were either of high (HF) or low (LF) phonotactic frequency. After familiarization, we observed, for both word and nonword conditions, decreased activation in the left posterior superior temporal gyrus, in the bilateral temporal pole and middle temporal gyri. At the same time, interaction analysis showed that the magnitude of decrease of activity in bilateral posterior temporal lobe was significantly smaller for LF nonwords, relative to words and HF nonwords. Decrease of activity in this area also correlated with the size of behavioral familiarization effects for LF nonwords. The results show that the posterior superior temporal gyrus plays a fundamental role during phonological learning. Its relationship to sublexical and lexical phonological processing as well as to phonological short-term memory is discussed.     

Long‐term memory effects on verbal short‐term memory: A replication study

The influence of lexico‐semantic language representations stored in long‐term memory (LTM) on short‐term memory (STM) performance has been studied extensively in adults. However, there are relatively few data on lexico‐semantic LTM effects on STM in children. On the other hand, the influence of phonological LTM effects on STM has been studied more extensively in children than in adults. In this study, we explored whether these different LTM effects on verbal STM could be replicated in both adults and children by administering immediate serial recall tasks (ISR) for high‐ and lowfrequency words, for high‐ and low‐imageability words, for words and non‐words, and for high and low phonotactic frequency non‐words to 6‐, 8‐, and 10‐year‐old children, to adolescents and to adults. Significant word frequency, lexicality and phonotactic frequency effects were observed in all age groups, as well as a word imageability effect which was, however, weaker than the other three effects. Our data suggest that LTM effects on STM are equivalent in both children and adults.     

Phonotactic cues for segmentation of fluent speech by infants

There is growing evidence that infants become sensitive to the probabilistic phonotactics of their ambient language sometime during the second half of their first year. The present study investigates whether 9-month-olds make use of phonotactic cues to segment words from fluent speech. Using the Headturn Preference Procedure, we found that infants listened to a CVC stimulus longer when the stimulus previously appeared in a sentential context with good phonotactic cues than when it appeared in one without such cues. The goodness of the phonotactic cues was estimated from the frequency with which the C.C clusters at the onset and offset of a CVC test stimulus (i.e. C.CVC.C) are found within and between words in child-directed speech, with high between-word probability associated with good cues to word boundaries. A similar segmentation result emerged when good phonotactic cues occurred only at the onset (i.e. C.CVC.C) or the offset (i.e. C.CVC.C) of the target words in the utterances. Together, the results suggest that 9-month-olds use probabilistic phonotactics to segment speech into words and that high-probability between-word clusters are interpreted as both word onsets and word offsets.     

Phonotactic probability influences speech production

Speakers are faster and more accurate at processing certain sound sequences within their language. Does this reflect the fact that these sequences are frequent or that they are phonetically less complex (e.g., easier to articulate)? It has been difficult to contrast these two factors given their high correlation in natural languages. In this study, participants were exposed to novel phonotactic constraints de-correlating complexity and frequency by subjecting the same phonological structure to varying degrees of probabilistic constraint. Participants' behavior was sensitive to variations in frequency, demonstrating that phonotactic probability influences speech production independent of phonetic complexity.     

Neuromagnetic evidence for the timing of lexical activation: an MEG component sensitive to phonotactic probability but not to neighborhood density

Evidence from electrophysiological measures such as ERPs (event-related potentials) and MEG (magnetoencephalography) suggest that the first evoked brain response component sensitive to stimulus properties affecting reaction times in word recognition tasks occurs at 300-400 ms. The present study used the stimulus manipulation of Vitevich and Luce (1999) to investigate whether the M350, an MEG response component peaking at 300-400 ms, reflects lexical or postlexical processing. Stimuli were simultaneously varied in phonotactic probability, which facilitates lexical activation, and in phonological neighborhood density, which inhibits the lexical decision process. The present results indicate that the M350 shows facilitation by phonotactic probability rather than inhibition by neighborhood density. Thus the M350 cannot be a postlexical component.     

Constraints on statistical computations at 10 months of age: the use of phonological features

Recently, several studies have argued that infants capitalize on the statistical properties of natural languages to acquire the linguistic structure of their native language, but the kinds of constraints which apply to statistical computations remain largely unknown. Here we explored French‐learning infants' perceptual preference for labial‐coronal (LC) words over coronal‐labial words (CL) words (e.g. preferring bat over tab) to determine whether this phonotactic preference is based on the acquisition of the statistical properties of the input based on a single phonological feature (i.e. place of articulation), multiple features (i.e. place and manner of articulation), or individual consonant pairs. Results from four experiments revealed that infants had a labial‐coronal bias for nasal sequences (Experiment 1) and for all plosive sequences (Experiments 2 and 4) but a coronal‐labial bias for all fricative sequences (Experiments 3 and 4), independently of the frequencies of individual consonant pairs. These results establish for the first time that constellations of multiple phonological features, defining broad consonant classes, constrain the early acquisition of phonotactic regularities of the native language.     

Phonological processes and the perception of phonotactically illegal consonant clusters

The perception of consonant clusters that are phonotactically illegal word initially in English (e.g., /tl/, /sr/) was investigated to determine whether listeners’ phonological knowledge of the language influences speech processing. Experiment 1 examined whether the phonotactic context effect (Massaro & Cohen, 1983), a bias toward hearing illegal sequences (e.g., /tl/) as legal (e.g., /tr/), is more likely due to knowledge of the legal phoneme combinations in English or to a frequency effect. In Experiment 2, Experiment 1 was repeated with the clusters occurring word medially to assess whether phonotactic rules of syllabification modulate the phonotactic effect. Experiment 3 examined whether vowel epenthesis, another phonological process, might also affect listeners’ perception of illegal sequences as legal by biasing them to hear a vowel between the consonants of the cluster (e.g., /talee/). Results suggest that knowledge of the phonotactically permissible sequences in English can affect phoneme processing in multiple ways.     

Estimating the Capacity of Phonological Short-term Memory

Two methods of assessing the capacity of phonological short-term memory that minimize support from long-term memory were compared in a sample of 7- and 8-year-old children. The children were tested on immediate serial recall of words and nonwords, and on the serial recognition of sequences composed of words and nonwords. Serial recognition scores were found to be highly related to children's accuracy of recall of nonwords composed of low-probability phonotactic combinations, but were independent of the long-term memory contributions to recall estimated in the serial recall experiment. Children with high vocabulary knowledge performed significantly better than low vocabulary children on both the recall and recognition measures. It is argued that the convergence of the two techniques lends substantial validity to their use as assessments of phonological storage capacity relatively free of long-term memory influence, and that the crucial difference between children varying in vocabulary knowledge lies in this storage capacity rather than the differential availability and use of long-term knowledge.     

Are phonological representations of printed and spoken language isomorphic? Evidence from the restrictions on unattested onsets

Are the phonological representations of printed and spoken words isomorphic? This question is addressed by investigating the restrictions on onsets. Cross-linguistic research suggests that onsets of rising sonority are preferred to sonority plateaus, which, in turn, are preferred to sonority falls (e.g., bnif [symbol: see text] bdif [symbol: see text] lbif). Of interest is whether these grammatical preferences constrain the recognition of auditory and printed words by speakers of English--a language in which such onsets are unattested. Five experiments compare phonological lexical decision responses to nonwords, including unattested onsets, through either aural or visual presentation. Results suggest that both hearers and readers are sensitive to the phonotactics of unattested onsets. However, the phonotactic generalizations of hearers and readers differ on their scope and source. Hearers differentiated all three types of onsets (e.g., bnif, bdif, and lbif), and their behavior implicated both grammatical and statistical constraints. In contrast, readers were able to differentiate only those structures similar to attested English onsets from dissimilar structures (i.e., bnif vs. bdif or lbif), and their preferences reflected statistical knowledge alone. These findings suggest that the phonological representations informing lexical decision to spoken and printed words are not isomorphic.     

Modeling the word recognition data of Vitevitch and Luce (1998): Is it ARTful?

Vitevitch and Luce (1998) showed that the probability with which phonemes co-occur in the language (phonotactic probability) affects the speed with which words and nonwords are named. Words with high phonotactic probabilities between phonemes were named more slowly than words with low probabilities, whereas with nonwords, just the opposite was found. To reproduce this reversal in performance, a model would seem to require not merely sublexical representations, but sublexical representations that are relatively independent of lexical representations. ARTphone (Grossberg, Boardman, & Cohen, 1997) is designed to meet these requirements. In this study, we used a technique called parameter space partitioning to analyze ARTphone’s behavior and to learn if it can mimic human behavior and, if so, to understand how. To perform best, differences in sublexical node probabilities must be amplified relative to lexical node probabilities to offset the additional source of inhibition (from top-down masking) that is found at the sublexical level.