Contrasting speech patterns in apraxia of speech and phonemic paraphasia

This study was designed to determine if perceptual phonological analysis would reveal distinctions between patients with apraxia of speech and patients with phonemic paraphasic speech. Test findings from 10 Broca's aphasics with apraxia of speech were compared to findings from 10 paraphasic speakers (5 conduction and 5 Wernicke's aphasics). Several marked differences were revealed. Predominant locus of errors and relative difficulty of different classes of phonemic segments were significant discriminators. There was a nonsignificant trend for substituted phonemes to be further from target phonetically in the paraphasic patients. In addition, the two groups showed certain consistent differences in the types of errors they produced. Apraxic patients produced many errors of transitionalization, while sequencing errors were more typical of the patients with phonemic paraphasia. The findings are interpreted in relation to a neuropsychological model of speech. It is suggested that phonemic paraphasia represents a breakdown mainly in the retrieval of phonological word patterns, while apraxia of speech is characterized predominantly by a disturbance in encoding phonological patterns into appropriate speech movements.     

Constraints upon word substitution speech errors

We explore the features of a corpus of naturally occurring word substitution speech errors. Words are replaced by more imageable competitors in semantic substitution errors but not in phonological substitution errors. Frequency effects in these errors are complex and the details prove difficult for any model of speech production. We argue that word frequency mainly affects phonological errors. Both semantic and phonological substitutions are constrained by phonological and syntactic similarity between the target and intrusion. We distinguish between associative and shared-feature semantic substitutions. Associative errors originate from outside the lexicon, while shared-feature errors arise within the lexicon and occur when particular properties of the targets make them less accessible than the intrusion. Semantic errors arise early while accessing lemmas from a semantic-conceptual input, while phonological errors arise late when accessing phonological forms from lemmas. Semantic errors are primarily sensitive to the properties of the semantic field involved, whereas phonological errors are sensitive to phonological properties of the targets and intrusions.     

Fragile X speech phonology in Finnish

Fragile X syndrome is a recently discovered relatively common syndrome linked with an anomaly of the X chromosome and causing handicaps of cognitive development especially in males. In the present phonological analysis we will discuss the sound patterns of two Finnish fragile X speakers, a five (borderline intelligence)- and an eight (mildly mentally retarded)-year-old boy. The fragile X syndrome is not necessarily linked with any anomalies of speech organs. The subjects could produce all Finnish speech sounds in isolated test words. However, in the present samples of connected speech they exhibited general dysphonology. What is noteworthy is that their phonological error patterns resembled each other to a great extent. Among the common features were the tendencies to substitute and omit phonemes. As for vowels, our results showed about one-half of the errors to be omissions. Labiality and quantity oppositions were quite resistant to substitution. Most substitution errors of place of consonants occurred in dentals. As for the feature of manner, /r/ and /s/ were the phonemes most prone for substitution. A tendency toward spirantization or /h/ sation was common for both patients. The number of additions was clearly lower than has been reported for English-speaking developmentally dyspraxic children and also for Finnish Broca's aphasics. The speech problems of our patients seemed to indicate higher level motor encoding problems of linguistic information rather than peripheral articulatory deficits.     

Interaction and representational integration: evidence from speech errors

We examine the mechanisms that support interaction between lexical, phonological and phonetic processes during language production. Studies of the phonetics of speech errors have provided evidence that partially activated lexical and phonological representations influence phonetic processing. We examine how these interactive effects are modulated by lexical frequency. Previous research has demonstrated that during lexical access, the processing of high frequency words is facilitated; in contrast, during phonetic encoding, the properties of low frequency words are enhanced. These contrasting effects provide the opportunity to distinguish two theoretical perspectives on how interaction between processing levels can be increased. A theory in which cascading activation is used to increase interaction predicts that the facilitation of high frequency words will enhance their influence on the phonetic properties of speech errors. Alternatively, if interaction is increased by integrating levels of representation, the phonetics of speech errors will reflect the retrieval of enhanced phonetic properties for low frequency words. Utilizing a novel statistical analysis method, we show that in experimentally induced speech errors low lexical frequency targets and outcomes exhibit enhanced phonetic processing. We sketch an interactive model of lexical, phonological and phonetic processing that accounts for the conflicting effects of lexical frequency on lexical access and phonetic processing.     

Beyond babytalk: Re-evaluating the nature and content of speech input to preverbal infants

Infant-directed maternal speech is an important component of infants’ linguistic input. However, speech from other speakers and speech directed to others constitute a large amount of the linguistic environment. What are the properties of infant-directed speech that differentiate it from other components of infants’ speech environment? To what extent should these other aspects be considered as part of the linguistic input? This review examines the characteristics of the speech input to preverbal infants, including phonological, morphological, and syntactic characteristics, specifically how these properties might support language development. While maternal, infant-directed speech is privileged in the input, other aspects of the environment, such as adult-directed speech, may also play a role. Furthermore, the input is variable in nature, dependent on the age and linguistic development of the infant, the social context, and the interaction between the infant and speakers in the environment.     

Motor movement matters: The flexible abstractness of inner speech

Inner speech is typically characterized as either the activation of abstract linguistic representations or a detailed articulatory simulation that lacks only the production of sound. We present a study of the speech errors that occur during the inner recitation of tongue-twister-like phrases. Two forms of inner speech were tested: inner speech without articulatory movements and articulated (mouthed) inner speech. Although mouthing one’s inner speech could reasonably be assumed to require more articulatory planning, prominent theories assume that such planning should not affect the experience of inner speech and, consequently, the errors that are “heard” during its production. The errors occurring in articulated inner speech exhibited the phonemic similarity effect and the lexical bias effect—two speech-error phenomena that, in overt speech, have been localized to an articulatory-feature-processing level and a lexical—phonological level, respectively. In contrast, errors in unarticulated inner speech did not exhibit the phonemic similarity effect—just the lexical bias effect. The results are interpreted as support for a flexible abstraction account of inner speech. This conclusion has ramifications for the embodiment of language and speech and for the theories of speech production.     

Social feedback to infants' babbling facilitates rapid phonological learning

Infants' prelinguistic vocalizations are rarely considered relevant for communicative development. As a result, there are few studies of mechanisms underlying developmental changes in prelinguistic vocal production. Here we report the first evidence that caregivers' speech to babbling infants provides crucial, real-time guidance to the development of prelinguistic vocalizations. Mothers of 9.5-month-old infants were instructed to provide models of vocal production timed to be either contingent or noncontingent on their infants' babbling. Infants given contingent feedback rapidly restructured their babbling, incorporating phonological patterns from caregivers' speech, but infants given noncontingent feedback did not. The new vocalizations of the infants in the contingent condition shared phonological form but not phonetic content with their mothers' speech. Thus, prelinguistic infants learned new vocal forms by discovering phonological patterns in their mothers' contingent speech and then generalizing from these patterns.     

The Frame Constraint on Experimentally Elicited Speech Errors in Japanese

The so-called syllable position effect in speech errors has been interpreted as reflecting constraints posed by the frame structure of a given language, which is separately operating from linguistic content during speech production. The effect refers to the phenomenon that when a speech error occurs, replaced and replacing sounds tend to be in the same position within a syllable or word. Most of the evidence for the effect comes from analyses of naturally occurring speech errors in Indo-European languages, and there are few studies examining the effect in experimentally elicited speech errors and in other languages. This study examined whether experimentally elicited sound errors in Japanese exhibits the syllable position effect. In Japanese, the sub-syllabic unit known as “mora” is considered to be a basic sound unit in production. Results showed that the syllable position effect occurred in mora errors, suggesting that the frame constrains the ordering of sounds during speech production.     

Simultaneous activation of reading mechanisms: evidence from a case of deep dyslexia

We report the performance of LC, a deep dyslexic. We investigated extensively her errors according to serial cognitive neuropsychological models of oral reading. Initial evaluation of her reading suggested impaired access to the phonological output lexicon (POL). Impaired grapheme-to-phoneme conversion (GPC) and semantic errors in reading suggested that LC read via an impoverished semantic route. However, a serial model of oral reading could not explain error differences in reading, picture naming, spontaneous speech, and repetition. Neologisms occurred in oral reading but not in spontaneous speech and repetition. Semantic errors in naming exceeded those in oral reading. To account for these different error patterns we propose that the semantic route, the direct route from the orthographic input lexicon to the POL, and GPC activate simultaneously during reading, converging at the POL to constrain phonological selection. These routes are modular but not functionally encapsulated. For LC, the POL receives ambiguous information due to degradation of all routes, causing reading errors.     

Irrelevant sound disrupts speech production: Exploring the relationship between short-term memory and experimentally induced slips of the tongue

To explore the relationship between short-term memory and speech production, we developed a speech error induction technique. The technique, which was adapted from a Japanese word game, exposed participants to an auditory distractor word immediately before the utterance of a target word. In Experiment 1, the distractor words that were phonologically similar to the target word led to a greater number of errors in speaking the target than did the dissimilar distractor words. Furthermore, the speech error scores were significantly correlated with memory span scores. In Experiment 2, memory span scores were again correlated with the rate of the speech errors that were induced from the task-irrelevant speech sounds. Experiment 3 showed a strong irrelevant-sound effect in the serial recall of nonwords. The magnitude of the irrelevant-sound effects was not affected by phonological similarity between the to-be-remembered nonwords and the irrelevant-sound materials. Analysis of recall errors in Experiment 3 also suggested that there were no essential differences in recall error patterns between the dissimilar and similar irrelevant-sound conditions. Weproposed two different underlying mechanisms in immediate memory, one operating via the phonological short-term memory store and the other via the processes underpinning speech production.     

Phonological neighborhood density in the picture naming of young children who stutter: preliminary study

The purpose of this study was to assess the effect of phonological neighborhood density on the speech reaction time (SRT) and errors of children who do and do not stutter during a picture-naming task. Participants were nine 3-5-year-old children who stutter (CWS) matched in age and gender to nine children who do not stutter (CWNS). Initial analyses indicated that both CWNS and CWS were significantly faster (i.e., exhibited shorter SRTs) and more accurate on phonologically sparse than phonologically dense words, findings consistent with those found with older children (Newman & German, 2002). Further analyses indicated that talker group differences in receptive language scores weakened these findings. These preliminary findings were taken to suggest that phonological neighborhood density appears to influence the picture-naming speed and accuracy of preschool-aged children. EDUCATIONAL OBJECTIVES: The reader will learn about and be able to: (1) recognize the relevance of examining phonological variables in relation to childhood stuttering; and (2) describe the method of measuring speech reaction times and errors during a picture-naming task as a means of assessing linguistic skills.     

Perceptual Bias in Speech Error Data Collection: Insights from Spanish Speech Errors

This paper studies the reliability and validity of naturalistic speech errors as a tool for language production research. Possible biases when collecting naturalistic speech errors are identified and specific predictions derived. These patterns are then contrasted with published reports from Germanic languages (English, German and Dutch) and one Romance language (Spanish). Unlike findings in the Germanic languages, Spanish speech errors show many patterns which run contrary to those expected from bias: (1) more phonological errors occur between words than within word; (2) word-initial consonants are less likely to participate in errors than word-medial consonants, (3) errors are equally likely in stressed and in unstressed syllables, (4) perseverations are more frequent than anticipations, and (5) there is no trace of a lexical bias. We present a new corpus of Spanish speech errors collected by many theoretically naïve observers (whereas the only corpus available so far was collected by two highly trained theoretically informed observers), give a general overview of it, and use it to replicate previous reports. In spite of the different susceptibility of these methods to bias, results were remarkably similar in both corpora and again contrary to predictions from bias. As a result, collecting speech errors “in the wild” seems to be free of bias to a reasonable extent even when using a multiple-collector method. The observed contrasting patterns between Spanish and Germanic languages arise as true cross-linguistic differences.     

Phonological error analysis, development and empirical evaluation.

A method of error analysis, designed to examine phonological and nonphonological reading and spelling processes, was developed from preliminary studies and theoretical background, including a linguistic model and the relationships between articulatory features of phonemes. The usefulness of this method as an assessment tool for phonological ability was tested on a group of normal subjects. The results from the error analysis helped clarify similarities and differences in phonological performance among the subjects and helped delineate differences between phonological performance in spelling (oral and written) and reading within the group of subjects. These results support the usefulness of this method of error analysis in assessing phonological ability. Also, these results support the position that phonological approximation of responses is an important diagnostic feature and merely cataloging errors as phonologically accurate or inaccurate is inadequate for assessing phonological ability.     

Investigation of phonological encoding through speech error analyses: achievements, limitations, and alternatives.

Phonological encoding in language production can be defined as a set of processes generating utterance forms on the basis of semantic and syntactic information. Most evidence about these processes stems from analyses of sound errors. In section 1 of this paper, certain important results of these analyses are reviewed. Two prominent models of phonological encoding, which are mainly based on speech error evidence, are discussed in section 2. In section 3, limitations of speech error analyses are discussed, and it is argued that detailed and comprehensive models of phonological encoding cannot be derived solely on the basis of error analyses. As is argued in section 4, a new research strategy is required. Instead of using the properties of errors to draw inferences about the generation of correct word forms, future research should directly investigate the normal process of phonological encoding.     

Phonological and articulatory impairment in Alzheimer's disease: a case series

We demonstrate that phonological and articulatory impairments may occur at presentation or early in the course of Alzheimer's disease, contrary to claims that these aspects of language production are relatively preserved until the final stages of this disease. Six patients with pathologically confirmed Alzheimer's disease (AD) and four patients with clinically diagnosed dementia of the Alzheimer's type (DAT) presented with one of five different clinical profiles: nonfluent progressive aphasia, mixed progressive aphasia, progressive aphasia diagnosed as DAT from neuropsychological assessment, initial amnestic syndrome with prominent phonological errors, and biparietal syndrome. Analysis of their conversational speech, single-word production, and performance of highly familiar series speech tasks such as counting revealed false start errors, phonological paraphasias, and/or articulatory difficulty. Neuropathological changes were located in left perisylvian regions consistent with speech and language impairment but atypical for Alzheimer's disease.     

Phonetic variability and prosodic structure in mothers

Spontaneous speech acoustics are highly variable. Such variability may be problematic for infants relying on phonological form to solve the segmentation problem. In the present study, acoustic measures of vowel duration and a computer model of speech segmentation were used to evaluate the problem of phonetic variability for a rhythm-based speech segmentation strategy. The specific questions under study were (1) whether or not mothers realized disyllabic vowel duration patterns consistently in spontaneous infant-directed speech, and (2) whether or not these patterns were distinctive enough in the context of an utterance to provide a useful cue for speech segmentation. Data from four English-speaking mothers indicated that the trochaic-like duration pattern may interact with phrase-position and with grammatical category, but when the resulting patterns are consistent, they provide useful segmentation cues for spontaneous infant-directed speech.     

A model of serial order problems in fluent, stuttered and agrammatic speech

Many models of speech production have attempted to explain dysfluent speech. Most models assume that the disruptions that occur when speech is dysfluent arise because the speakers make errors while planning an utterance. In this contribution, a model of the serial order of speech is described that does not make this assumption. It involves the coordination or 'interlocking' of linguistic planning and execution stages at the language-speech interface. The model is examined to determine whether it can distinguish two forms of dysfluent speech (stuttered and agrammatic speech) that are characterized by iteration and omission of whole words and parts of words.     

Are phonological influences on lexical (mis)selection the result of a monitoring bias?

A monitoring bias account is often used to explain speech error patterns that seem to be the result of an interactive language production system, like phonological influences on lexical selection errors. A biased monitor is suggested to detect and covertly correct certain errors more often than others. For instance, this account predicts that errors that are phonologically similar to intended words are harder to detect than those that are phonologically dissimilar. To test this, we tried to elicit phonological errors under the same conditions as those that show other kinds of lexical selection errors. In five experiments, we presented participants with high cloze probability sentence fragments followed by a picture that was semantically related, a homophone of a semantically related word, or phonologically related to the (implicit) last word of the sentence. All experiments elicited semantic completions or homophones of semantic completions, but none elicited phonological completions. This finding is hard to reconcile with a monitoring bias account and is better explained with an interactive production system. Additionally, this finding constrains the amount of bottom-up information flow in interactive models.