The selective impairment of phonological processing in speech production

We report the naming performance of a patient (DM) with a fluent progressive aphasia who made phonological errors in all language production tasks. The pattern of errors in naming was strikingly clear: DM made very many phonological errors that resulted almost always in nonword responses. The complete absence of semantic errors and the very low ratio of formal errors relative to nonword errors (1.6:30.3) in DM's performance are discussed in the context of recent claims about the nature of naming deficits in fluent aphasics. We argue that DM's performance makes highly improbable the claim that fluent aphasia results from global lesions affecting all levels of the lexical access system equally.     

Contrasting effects of phonological priming in aphasic word production

Two fluent aphasics, IG and GL, performed a phonological priming task in which they repeated an auditory prime then named a target picture. The two patients both had selective deficits in word production: they were at or near ceiling on lexical comprehension tasks, but were significantly impaired in picture naming. IG's naming errors included both semantic and phonemic paraphasias, as well as failures to respond, whereas GL's errors were mainly phonemic and formal paraphasias. The two patients responded very differently to phonological priming: IG's naming was facilitated (both accuracy and speed) only by begin-related primes (e.g. ferry-feather), whereas GL benefited significantly only from end-related primes (e.g. brother-feather), showing no more than a facilitatory trend with begin-related primes. We interpret these results within a two-stage model of word production, in which begin-related and end-related primes are said to operate at different stages. We then discuss implications for models of normal and aphasic word production in general and particularly with respect to sequential aspects of the phonological encoding process.     

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.     

Self-monitoring behavior in a case of severe auditory agnosia with aphasia

This case report describes an unusual combination of speech and language deficits secondary to bilateral infarctions in a 62-year-old woman. The patient was administered an extensive series of speech, language, and audiologic tests and was found to exhibit a fluent aphasia in which reading and writing were extremely well preserved in comparison to auditory comprehension and oral expression, and a severe auditory agnosia. In spite of her auditory processing deficits, the patient exhibited unexpected self-monitoring ability and the capacity to form acoustic images on visual tasks. The manner in which she corrected and attempted to correct her phonemic errors, while ignoring semantic errors, suggests that different mechanisms may underlie the monitoring of these errors.     

Production deficits in aphasia: A voice-onset time analysis

An experimental study was conducted to examine phonetic and phonemic deficits in the speech production of aphasics. Subjects included four Broca's aphasics, four Conduction aphasics, five Wernicke's aphasics, one nonaphasic dysarthric patient, and four normal controls. The subjects read a list of words containing word-initial stop consonants which were subsequently measured acoustically for voice-onset time. The results showed that Broca's aphasics exhibit a more severe production disorder than Conduction aphasics who in turn exhibit a more severe disorder than Wernicke's aphasics, in accord with clinical observations. In addition, although Broca's aphasics produced both phonetic and phonemic errors, the results showed that they have a pervasive phonetic disorder which affects their correct target productions as well as the total number of phonetic errors produced. This deficit however seems to be a speech deficit rather than a low-level motor control problem. In contrast, the Wernicke's aphasics show a deficit characterized by isolated phonemic mistargeting errors. Finally, the pattern of productions for the Conduction aphasics indicates that some patients show a predominantly phonetic disorder similar to the Broca's aphasics and others show predominantly a phonemic disorder similar to the Wernicke's aphasics.     

Inner speech slips exhibit lexical bias, but not the phonemic similarity effect

Inner speech, that little voice that people often hear inside their heads while thinking, is a form of mental imagery. The properties of inner speech errors can be used to investigate the nature of inner speech, just as overt slips are informative about overt speech production. Overt slips tend to create words (lexical bias) and involve similar exchanging phonemes (phonemic similarity effect). We examined these effects in inner and overt speech via a tongue-twister recitation task. While lexical bias was present in both inner and overt speech errors, the phonemic similarity effect was evident only for overt errors, producing a significant overtness by similarity interaction. We propose that inner speech is impoverished at lower (featural) levels, but robust at higher (phonemic) levels.     

Effect of sentence length on the production of linguistic stress by left- and right-hemisphere-damaged patients

An acoustical/perceptual study of phonemic stress (e.g., HOTdog vs. hot DOG) was conducted to evaluate the effect of sentence length on stress production after brain damage. Productions of phonemic stress pairs were elicited in sentence contexts of increasing length from eight left-hemisphere-damaged nonfluent (LHD-NFL), fluent LHD-FL), right-hemisphere-damaged (RHD), and normal speakers (n = 32). Tape recordings of subjects' productions were presented to na?ve listeners for perceptual identification of stress placement. Acoustic analysis focused on fundamental frequency, duration, and intensity of the initial and final syllables as well as pause duration between syllables. Perceptual tests indicated that regardless of sentence length, all brain-damaged groups exhibited an impairment in the production of linguistic stress when compared to normals. The LHD-NFL group experienced the greatest difficulty in signaling stress contrasts, followed in order by the LHD-FL and RHD groups. In medium-length sentences, the LHD-FL group's performance was degraded by comparison to short-length sentences. Acoustic analysis showed that pause duration was the strongest predictor of phonemic stress for all groups. Acoustic profiles of the RHD group were similar qualitatively to those of normals, but differed quantitatively in terms of magnitude of effect associated with shifts in stress patterns. Findings are brought to bear on the nature of the stress production deficit after unilateral brain damage, the role of the right hemisphere in linguistic prosody, and the concept of "subtle phonetic deficit" in fluent aphasia.     

Phonemic behavior of aphasic patients with posterior cerebral lesions

The investigation analyzed the phonemic paraphasic errors of 10 asphasic patients with posterior cerebral lesions. The results indicated that paraphasic speech is characterized by complex confusions, often occurring at the ends of words and often involving phonemic transpositions. Many of the unusual and unexpected phonemic errors appeared to be due to simultaneous semantic and phonologic confusions.     

Mechanisms underlying writing and speech in aphasia

As a parallel to the dual decoding concept for processing of written language we proposed that phonological encoding does not necessarily occur in writing and that the phonemic and graphemic subsystems can be independent on the one-word level. This hypothesis was tested by comparing oral and written performance in a picture-naming task in Broca's and Wernicke's aphasics. In addition, the residual tacit knowledge of the orthographic properties of the names of the pictures was examined with a multiple-choice recognition task. The principal finding is that Broca's aphasics who were better in written than in oral naming showed more graphemically and semantically motivated errors than aphasics who were better in oral than in written naming, the latter producing more phonemically motivated errors. This result supports the dual encoding concept for writing on the singleword level, implying a direct route from the mental lexicon to the graphemic system in parallel with a route mediated by the phonemic system. Multiple-choice recognition was found to be superior to both oral and written performance in both Broca's and Wernicke's aphasics.     

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.     

Word recognition in a phonemic dyslexic patient

The systems underlying word recognition were investigated in a single case study of a patient (K.F.) with an acquired dyslexia. His reading performance was related to parts of speech, word frequency and word concreteness, and his reading errors were analysed. There was a very striking difference between his ability to read concrete and abstract words. Furthermore visual errors, which could not be attributed to a deficit at a peripheral level, predominated; phonemic errors did not occur. It is argued that these findings support a dual encoding model of word recognition, the present case illustrating the impairment of the phonemic route, a direct graphemic-semantic route being relatively spared. These findings and interpretation are for the most part consistent with Marshall and Newcombe's (1973) studies of acquired dyslexia. The present findings are discussed in terms of more general theories of word recognition.     

Transcortical sensory aphasia: Evidence for subtypes

Impaired auditory comprehension and fluent but semantically empty speech in conjunction with preserved repetition characterize the syndrome of transcortical sensory aphasia (TSA). Repetition, however, may be mediated by at least two distinct processes--a lexical process that may involve the recognition and subsequent activation of discrete stored word representations and a nonlexical process that involves phonologic decoding and immediate phonologic encoding from immediate memory. We investigated the spontaneous speech, reading, and tendency to recognize and spontaneously correct syntactic errors in four patients with TSA: this analysis suggests there are two subtypes of TSA. We contend that in one subtype both the lexical and direct repetition (or speech production) mechanisms are preserved, but in the second subtype the lexical mechanism is disrupted and repetition is mediated by the nonlexical mechanism.     

Effects of morphological complexity on phonological output deficits in fluent and nonfluent aphasia

This study examined the effects of morphological complexity on aphasic speakers with lexical-phonological output deficits. Subjects were two fluent and two nonfluent aphasic speakers who repeated morphologically simple words at the same level of accuracy and whose errors were virtually all phonological in nature. They were asked to repeat a variety of morphologically complex (i.e., affixed) words. Results were interpreted within our two-stage model of lexical-phonological production (Kohn & Smith, 1994, 1995), which we expand to include a distinction between derivational and inflectional morphology. When comparing overall performance levels between morphologically simple and complex words, only three subjects exhibited more difficulty repeating the morphologically complex targets. Nevertheless, when comparing repetition accuracy between different types of morphologically complex words (e.g., derived vs. inflected), all four subjects displayed similar patterns. These findings suggested that while morphological complexity has different effects on the two stages within the lexical-phonological output system, the relative effects of different morphological structures are constant. At the level of error analysis, patterns of affix errors distinguished the nonfluent from the fluent subjects in ways that are reminiscent of the affix errors associated with agrammatic and paragrammatic speech. This finding raised questions concerning the relationship between morphosyntactic and morphophonological deficits.     

Priority and position

Positional goods are goods whose relative amount determines their absolute value. Many goods appear to have positional aspects. For example, one’s relative standing in the distribution of education and wealth may determine one’s absolute condition with respect to goods like employment opportunities, self-respect, and social inclusion. Positional goods feature in recent arguments from T.M. Scanlon, Brian Barry, and Harry Brighouse and Adam Swift that assert that we should favor egalitarian distributions of positional goods even if we reject equality as a fundamental principle of distributive justice. With respect to positional goods, worsening the better off is required to better the worse off. Thus, we have reason to “level down” goods such as education and wealth in order to benefit those worse off with respect to the value of those goods. I argue that the allegedly positional aspects of the goods in question are not actually positional. Moreover, leveling down these goods risks self-defeat: it may produce a net decrease in the value of the shares of individuals with less of such goods. If so, leveling down measures would fail on their own terms.     

Deep dysphasia: analysis of a rare form of repetition disorder

"Deep dysphasia" is the parallel in repetition to the reading impairment deep dyslexia. Our patient, S.M., showed part of speech, word/nonword, and concreteness effects in repetition, and he made semantic errors, but his oral reading was relatively spared. Further testing indicated that S.M. did not have difficulty perceiving spoken stimuli or deciding their lexical status, but he was deficient at semantically processing spoken words. Moreover, his phonemic memory was severely impaired. We argue that the routes for repetition (lexical and nonlexical) that function without semantic mediation were defective and that deficits in phonemic memory further diminished their effectiveness, since initial phonological encoding of spoken words was not available to guide the output stages of phonological processing. In addition, the semantically mediated route for repetition was unreliable because semantic processing was faulty and S.M. could not accurately label concepts.     

Cascading influences on the production of speech: evidence from articulation

Recent investigations have supported the suggestion that phonological speech errors may reflect the simultaneous activation of more than one phonemic representation. This presents a challenge for speech error evidence which is based on the assumption of well-formedness, because we may continue to perceive well-formed errors, even when they are not produced. To address this issue, we present two tongue-twister experiments in which the articulation of onset consonants is quantified and compared to baseline measures from cases where there is no phonemic competition. We report three measure of articulatory variability: changes in tongue-to-palate contact using electropalatography (EPG, Experiment 1), changes in midsagittal spline of the tongue using ultrasound (Experiment 2), and acoustic changes manifested as voice-onset time (VOT). These three sources provide converging evidence that articulatory variability increases when competing onsets differ by one phonological feature, but the increase is attenuated when onsets differ by two features. This finding provides clear evidence, based solely on production, that the articulation of phonemes is influenced by cascading activation from the speech plan.     

On-Air Slips of the Tongue: A Psycholinguistic-Acoustic Analysis

The sixteen SOTs examined are on-air ones produced by native English TV presenters and anchors. Although these SOTs seem funny, they reflect a great deal about how naturalistic speech is assembled and produced. Acoustic analysis is also brought to bear on the present investigation with the aim of providing accurate findings. Several psycholinguistic models are invoked in the analysis, and Praat 6 is used to provide spectrograms and waveforms for the errors detected. The present study concludes that the SOTs examined in the present corpus reveal much about the processing of erroneous speech. Substitution errors, being the most prominent, exhibit uniform processing through a replacement on phonemic or higher levels. As for anticipation errors, they prove to be irregular in their production. Other errors are sparse in the present corpus, and cannot be generalized over a wide range of instances, since they occur either once or twice.

     

Fluent versus nonfluent primary progressive aphasia: a comparison of clinical and functional neuroimaging features

To better characterize fluent and nonfluent variants of primary progressive aphasia (PPA). Although investigators have recognized both fluent and nonfluent patients with PPA, the clinical and neuroimaging features of these variants have not been fully defined. We present clinical and neuropsychological data on 47 PPA patients comparing the fluent (n=21) and nonfluent (n=26) subjects. We further compared language features with PET/SPECT data available on 39 of these patients. Compared to the nonfluent PPA patients, those with fluent PPA had greater impairment of confrontational naming and loss of single word comprehension. They also exhibited semantic paraphasic errors and loss of single word comprehension. Patients with nonfluent PPA were more likely to be female, were more often dysarthric, and exhibited phonological speech errors in the absence of semantic errors. No significant differences were seen with regard to left hemisphere abnormalities, suggesting that both variants result from mechanisms that overlap frontal, temporal, and parietal regions. Of the language measures, only semantic paraphasias were strongly localized, in this case to the left temporal lobe. Fluent and nonfluent forms of PPA are clinically distinguishable by letter fluency, single word comprehension, object naming, and types of paraphasic errors. Nevertheless, there is a large amount of overlap between dysfunctional anatomic regions associated with these syndromes.     

The effects of semantic and phonemic prestimulation cues on picture naming in aphasia.

In this study of auditory prestimulation cues, picture naming performances under phonemic and semantic conditions were compared to picture naming performance under a neutral condition. Twenty aphasic subjects named 324 pictures (108 pictures x 3 conditions) each. Responses were scored using a coding system adapted by the investigator from classification systems used by Williams and Canter (1982) and Kohn and Goodglass (1985). Results indicated that naming accuracy was facilitated by phonemic and semantic cues. An examination of the distribution of errors under the three conditions revealed systematic effects of phonemic and semantic cues on the frequency of occurrence of specific error types. Increases in semantic paraphasia proportion scores and decreases in unrelated word error proportion scores were associated with the semantic condition, while increases in phonemic paraphasia proportion scores were associated with the phonemic condition. The finding that naming performance of aphasic adults varies as a function of the type of information provided by the cue is discussed in relation to cascade visual confrontation naming models.