Evidence of Absence: Abstract Metrical Structure in Speech Planning

Rhythmic structure in speech is characterized by sequences of stressed and unstressed syllables. A large body of literature suggests that speakers of English attempt to achieve rhythmic harmony by evenly distributing stressed syllables throughout prosodic phrases. The question remains as to how speakers plan metrical structure during speech production and whether it is planned independently of phonemes. To examine this, we designed a tongue twister task consisting of disyllabic word pairs with overlapping phonological segments and either matching or non-matching metrical structure. Results showed that speakers had more difficulty producing metrically regular word pairs, compared to irregular pairs; that is, word pairs with irregular meter had faster productions and fewer speech errors in this production task. This finding of metrical regularity inhibiting production is inconsistent with an abstract metrical structure that is planned independently of phonemes at the point of phonological encoding.

Cascading activation in phonological planning and articulation: Evidence from spontaneous speech errors

Speaking involves both retrieving the sounds of a word (phonological planning) and realizing these selected sounds in fluid speech (articulation). Recent phonetic research on speech errors has argued that multiple candidate sounds in phonological planning can influence articulation because the pronunciation of mis-selected error sounds is slightly skewed towards unselected target sounds. Yet research to date has only examined these phonetic distortions in experimentally-elicited errors, leaving doubt as to whether they reflect tendencies in spontaneous speech. Here, we analyzed the pronunciation of speech errors of English-speaking adults in natural conversations relative to matched correct words by the same speakers, and found the conjectured phonetic distortions. Comparison of these data with a larger set of experimentally-elicited errors failed to reveal significant differences between the two types of errors. These findings provide ecologically-valid data supporting models that allow for information about multiple planning representations to simultaneously influence speech articulation.

Delayed Phonological Encoding in Stuttering: Evidence from Eye Tracking

Stuttering is a multifactorial disorder that is characterized by disruptions in the forward flow of speech believed to be caused by differences in the motor and linguistic systems. Several psycholinguistic theories of stuttering suggest that delayed or disrupted phonological encoding contributes to stuttered speech. However, phonological encoding remains difficult to measure without controlling for the involvement of the speech-motor system. Eye-tracking is proposed to be a reliable approach for measuring phonological encoding duration while controlling for the influence of speech production. Eighteen adults who stutter and 18 adults who do not stutter read nonwords under silent and overt conditions. Eye-tracking was used to measure dwell time, number of fixations, and response time. Adults who stutter demonstrated significantly more fixations and longer dwell times during overt reading than adults who do not stutter. In the silent condition, the adults who stutter produced more fixations on the nonwords than adults who do not stutter, but dwell-time differences were not found. Overt production may have resulted in additional requirements at the phonological and phonetic levels of encoding for adults who stutter. Direct measurement of eye-gaze fixation and dwell time suggests that adults who stutter require additional processing that could potentially delay or interfere with phonological-to-motor encoding.

Tone slips in Cantonese: Evidence for early phonological encoding

This article examines speech errors in Cantonese with the aim of fleshing out a larger speech production architecture for encoding phonological tone. A corpus was created by extracting 2462 speech errors, including 668 tone errors, from audio recordings of natural conversations. The structure of these errors was then investigated in order to distinguish two contemporary approaches to tone in speech production. In the tonal frames account, tone is encoded like metrical stress, represented in abstract structural frames for a word. Because tone cannot be mis-selected in tonal frames, tone errors are expected to be rare and non-contextual, as observed with stress. An alternative is that tone is actively selected in phonological encoding like phonological segments. This approach predicts that tone errors will be relatively common and exhibit the contextual patterns observed with segments, like perseveration and anticipation. In our corpus, tone errors are the second most common type of error, and the majority of errors exhibit contextual patterns that parallel segmental errors. Building on prior research, a two-stage model of phonological tone encoding is proposed, following the patterns seen in tone errors: Tone is phonologically selected concurrently with segments, but then sequentially assigned after segments to a syllable.

Cross-Situational Learning of Phonologically Overlapping Words Across Degrees of Ambiguity

Cross-situational word learning (XSWL) tasks present multiple words and candidate referents within a learning trial such that word-referent pairings can be inferred only across trials. Adults encode fine phonological detail when two words and candidate referents are presented in each learning trial (2 × 2 scenario; Escudero, Mulak, & Vlach, ). To test the relationship between XSWL task difficulty and phonological encoding, we examined XSWL of words differing by one vowel or consonant across degrees of within-learning trial ambiguity (1 × 1 to 4 × 4). Word identification was assessed alongside three distractors. Adults finely encoded words via XSWL: Learning occurred in all conditions, though accuracy decreased across the 1 × 1 to 3 × 3 conditions. Accuracy was highest for the 1 × 1 condition, suggesting fast-mapping is a stronger learning strategy here. Accuracy was higher for consonant than vowel set targets, and having more distractors from the same set mitigated identification of vowel set targets only, suggesting possible stronger encoding of consonants than vowels.

Phonological neighborhood effect in spontaneous speech in adults who stutter

PURPOSE

The study examined the relationship between word-form similarity network (phonological neighborhood) and stuttering occurrence in spontaneous speech in adults. The study asked whether neighborhood characteristics, including the number of neighbors (neighborhood density) and the average word frequency among neighbors (neighborhood frequency), differentiate stuttered from fluent words within spontaneous speech samples, and more specifically, whether neighborhood characteristics facilitate speech fluency in adults who stutter.

METHOD

Spontaneous speech samples were collected from 14 adults who stutter, including 7 with mild stuttering and 7 with severe stuttering. Each stuttered word was matched with a fluently produced word within the sample, controlling for multiple lexical factors. Neighborhood density and neighborhood frequency were compared between the stuttered and matched fluent words.

RESULTS

Adults stuttered on words with lower neighborhood density, compared to fluently produced words, with similar patterns in the two severity subgroups. There appeared to be a marginal difference between single-syllable whole-word repetition and the other stuttering typologies.

CONCLUSION

Neighborhood density facilitates fluent word production in spontaneous speech in adults who stutter, regardless of stuttering severity. This finding adds to the evidence supporting that phonological encoding plays a role in stuttering in naturalistic, spontaneous speech in adults.

The prosodic domain of phonological encoding: Evidence from speech errors

Phonological encoding of segments is thought to occur within a prosodically-defined frame, but it is not clear which of the constituent/s within the prosodic hierarchy (syllables, phonological words, intonational phrases and utterances) serve/s as the domain of phonological encoding. This experiment investigated whether segmental speech errors elicited in tongue-twisters were influenced by position within prosodic constituents above the level of the phonological word. Forty-four participants produced six repetitions each of 40 two-intonational phrase tongue-twisters with error-prone word-initial "target" segments in phrase-initial and phrase-final words. If the domain of phonological encoding is the intonational phrase, we hypothesised that segments within a current intonational phrase would interact in more errors than would segments across intonational phrase boundaries. Participants made more anticipatory than perseveratory errors on target segments in phrase-initial words as predicted. They also made more perseveratory than anticipatory errors on targets in phrase-final words, but only in utterance-final phrases. These results suggest that the intonational phrase is one domain of phonological encoding, and that segments for upcoming phrases are activated while current phrases are being articulated.

Uniqueness Point Effects during Speech Planning in Adults Who Do and Do Not Stutter

BACKGROUND/AIMS

Previous studies employing a variety of tasks have demonstrated that adults who stutter (AWS) pre-sent with phonological encoding differences compared to adults who do not stutter (AWNS). The present study examined whether atypical preverbal monitoring also influenced AWS performance during one such paradigm - the silent phoneme monitoring task. Specifically, we investigated whether monitoring latencies for AWS were accelerated after the word's uniqueness point - the phoneme that isolates the word from all lexical competitors - as observed for AWNS when monitoring internal and external speech.

METHODS

Twenty adults (10 AWS, 10 AWNS) completed a silent phoneme monitoring task using stimuli which contained either (a) early uniqueness points (EUP), (b) late uniqueness points, or (c) no uniqueness point (NUP). Response latency when identifying word-final phonemes was measured.

RESULTS

AWNS exhibited the expected uniqueness point effect when monitoring internal speech; word-final phonemes were accessed more rapidly for words with EUP than NUP. In contrast, AWS did not differ in the phoneme monitoring speed. That is, AWS did not exhibit the expected uniqueness point effects.

CONCLUSION

Findings suggest that inefficient or atypical preverbal monitoring may be present in AWS and support theories that implicate the internal speech monitor as an area of deficit.

Length effects in pseudo-word spelling: stronger in dyslexic than in non-dyslexic students

It is often discussed whether dyslexics show a deviant pattern of reading and spelling development when compared to typically developing students, or whether they follow the same pattern as other students, only at markedly slower rate. The present cross-sectional study investigated phonological encoding skills in dyslexic Danish students. We compared dyslexic and non-dyslexic students from grades 3, 5, 7, and 9 and examined whether effects of item length were stronger in the dyslexic groups. Mixed between-within subjects analyses of variance revealed significant interactions between dyslexia status and item length as the dyslexics at all grade levels were more affected by item length than their non-dyslexic peers. A marked developmental delay was apparent as the dyslexic group from grade 9 performed on approximately the same level as the non-dyslexic group from grade 3. Although the overall difference between these two groups was not significant, a significant interaction between dyslexia status and item length remained because the grade 9 dyslexics were more affected by item length than the younger non-dyslexic students. This difference in error profiles suggests a difference in the developmental patterns of dyslexic vs. non-dyslexic students.

Time course of syllabic and sub-syllabic processing in Mandarin word production: Evidence from the picture-word interference paradigm

The time course of phonological encoding in Mandarin monosyllabic word production was investigated by using the picture-word interference paradigm. Participants were asked to name pictures in Mandarin while visual distractor words were presented before, at, or after picture onset (i.e., stimulus-onset asynchrony/SOA = -100, 0, or +100 ms, respectively). Compared with the unrelated control, the distractors sharing atonal syllables with the picture names significantly facilitated the naming responses at -100- and 0-ms SOAs. In addition, the facilitation effect of sharing word-initial segments only appeared at 0-ms SOA, and null effects were found for sharing word-final segments. These results indicate that both syllables and subsyllabic units play important roles in Mandarin spoken word production and more critically that syllabic processing precedes subsyllabic processing. The current results lend strong support to the proximate units principle (O'Seaghdha, Chen, & Chen, 2010), which holds that the phonological structure of spoken word production is language-specific and that atonal syllables are the proximate phonological units in Mandarin Chinese. On the other hand, the significance of word-initial segments over word-final segments suggests that serial processing of segmental information seems to be universal across Germanic languages and Chinese, which remains to be verified in future studies.

Negative induced mood influences word production: An event-related potentials study with a covert picture naming task

The present event-related potentials (ERPs) study investigated the effects of mood on phonological encoding processes involved in word generation. For this purpose, negative, positive and neutral affective states were induced in participants during three different recording sessions using short film clips. After the mood induction procedure, participants performed a covert picture naming task in which they searched letters. The negative compared to the neutral mood condition elicited more negative amplitudes in a component peaking around 290ms. Furthermore, results from source localization analyses suggested that this activity was potentially generated in the left prefrontal cortex. In contrast, no differences were found in the comparison between positive and neutral moods. Overall, current data suggest that processes involved in the retrieval of phonological information during speech generation are impaired when participants are in a negative mood. The mechanisms underlying these effects were discussed in relation to linguistic and attentional processes, as well as in terms of the use of heuristics.

Phonological memory in young children who stutter

This study investigated phonological memory in 5- and 6-year old children who stutter. Participants were 11 children who stutter matched on general language abilities, maternal education level, and sex to 11 typically fluent children. Participants completed norm-referenced nonword repetition and digit span tasks, as well as measures of expressive and receptive vocabulary and articulation. The nonword repetition task included stimuli that ranged from 1 to 7 syllables, while the digit naming task contained number strings containing 2-10 digits. Standardized tests of vocabulary and articulation abilities were tested as well. Groups were comparable on measures expressive vocabulary, receptive vocabulary, and articulation. Despite the fact that the majority of participants scored within typical limits, young children who stutter still performed significantly less well than children who do not stutter on the nonword repetition task. No between-group differences were revealed in the digit naming task. Typically fluent children demonstrated strong correlations between phonological memory tasks and language measures, while children who stutter did not. These findings indicate that young children who stutter may have sub-clinical differences in nonword repetition.

Serial order in word form retrieval: New insights from the auditory picture-word interference task

One important theoretical question about word production concerns whether the phonemes of a word are retrieved in parallel or in sequential order. To address this question, Meyer and Schriefers (Journal of Experimental Psychology: Learning, Memory, and Cognition 17:1146-1160, 1991) used an auditory picture-word interference task and manipulated the position of the phonemes shared between a distractor word and a target picture. They found that begin-related distractors (e.g., boat-bone) facilitated naming times when they were presented within 150 ms before or after the picture, whereas end-related distractors (e.g., cone-bone) were effective only if presented within 150 ms after the picture. This suggested that the word's end phonemes were activated later than the beginning ones. However, it remained unclear whether these effects genuinely reflected facilitation at the level of phonological retrieval. In this study, we examined later distractor presentation onsets, so that the distractors had little opportunity to influence earlier, lexical selection processes. At the latest onset tested, end-related-but not begin-related-distractors significantly facilitated naming. We concluded that late-presented distractors do indeed influence phonological encoding, and that their asymmetric effects support a sequential model of phoneme retrieval.

Practice and retention of nonwords in adults who stutter

PURPOSE

We investigated short-term practice and retention of nonwords in 10 adults who stutter (Mean age=30.7 years, SD=15.1) and age and sex-matched 10 control participants (Mean age=30.8 years, SD=14.9).

METHODS

Participants were required to repeat nonwords varying in length (3, 4, and 6 syllables), phonotactic constraint (PC vs. NPC, on 3-syllable nonwords only), and complexity (simple, complex). They were tested twice with 1h gap between sessions.

RESULTS

Logistic mixed model of speech accuracy revealed that the AWS showed a significantly lower probability of correct responses with increasing length and complexity. Analysis of speech kinematics revealed practice effects within Session 1 in AWS seen as a reduction in movement variability for the 3-syllable nonwords; the control group was performing at ceiling at this length. For the 4-syllable nonwords, the control group showed a significant reduction in movement variability with practice, and retained this reduction in Session 2, while the AWS group did not show practice or retention. Group differences were not evident at the 6-syllable level.

CONCLUSIONS

Group differences in speech accuracy suggest differences in phonemic encoding and/or speech motor processes. Group differences in changes in movement variability within and between sessions suggest reduced practice and retention in AWS. Relevance of the combined use of both behavioral and kinematic measures to interpret the nature of the skill acquisition deficit in persons who stutter is discussed.

EDUCATIONAL OBJECTIVES

At the end of this activity the reader will be able to: (a) summarize the process of skill acquisition; (b) discuss the literature on skill acquisition deficits in adults who stutter, (c) summarize the differences between AWS and control participants in speech accuracy and speech kinematics with short-term practice and retention of nonwords, (d) discuss potential research directions in the area of skill acquisition in AWS.

Phonological encoding of young children who stutter

PURPOSE

Several empirical studies suggest that children who stutter, when compared to typically fluent peers, demonstrate relatively subtle, yet robust differences in phonological encoding. Phonological encoding can be measured through the use of tasks that reflect the underlying mechanisms of phonological processing, such as phonological awareness. This study investigated the phonological encoding abilities of five- and six-year old children who stutter.

METHODS

Young children who stutter were paired according to language ability, maternal education, and sex to their typically fluent peers. Participants completed multiple measures of phonological awareness abilities (i.e., sound matching, phoneme blending, elision), as well as measures of expressive and receptive vocabulary and articulation.

RESULTS

Young children who stutter performed significantly less well than nonstuttering peers on tasks of elision and sound blending. No between-group differences were found in sound matching abilities or in any of the background language measures.

CONCLUSIONS

Results suggest that young children who stutter have subtle, yet robust, linguistic differences in certain aspects of phonological encoding that may contribute to an unstable language planning system in young children who stutter.

EDUCATIONAL OBJECTIVES

The reader will be able to: (a) describe how phonological awareness can inform our understanding of phonological encoding; (b) summarize the findings of previously published studies that examined some aspects of phonological awareness in children who do and do not stutter; and (c) compare the results of the current study with other investigations of phonological awareness skills in children who stutter and their typically fluent peers.