A study of repetition in aphasic patients

The ability of the aphasic patient to repeat a message is a capacity of considerable diagnostic value. While it is well known that certain aphasic groups (e.g., transcortical aphasics) repeat better than other groups (e.g., conduction aphasics), possible qualitative differences among the groups have not been subjected to analysis. To secure information on repetition profiles in various aphasic subgroups, a test consisting of 11 types of items, presented under conditions of both immediate and delayed recall, was administered to eight groups of aphasic patients. The results documented a significant difference across aphasic groups, one related to site of lesion but not to severity of comprehension defect. Performance proved to be a joint product of the length and the meaningfulness of the stimulus items. The delayed condition aided Broca's aphasics and impeded anomic aphasics; in addition, nonsense syllables proved to be easier on immediate recall, while meaningful stimuli, particularly those which were number related, were relatively easier on delayed recall. Finally, sound errors were more likely to be made by Broca's and “mixed anterior” aphasics, while meaning errors were particularly prominent among conduction aphasics. These results are discussed in terms of the mechanisms which may mediate repetition in aphasic patients.     

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.     

Visual and phonological codes in repetition blindness.

Repetition blindness (RB) is the inability to detect or recall a repeated word in rapid serial visual presentation. The role of visual versus phonological (name) similarity in RB was examined. RB was found for single letters, whether printed in the same or different cases, and for single digits, whether represented verbally (nine), as arabic numerals (9), or in a mixture of the 2 formats. Hence, visual similarity is not necessary to produce RB. RB was obtained between homophonic pairs (won/one), showing that phonological similarity is sufficient to produce RB, although visual identity also contributes to RB. It is proposed that RB results when the codes used for initial registration of the targets in short-term memory are similar. This initial code may be predominantly visual or predominantly phonological.     

Phoneme frequency effects in jargon aphasia: a phonological investigation of nonword errors

This study investigates the nonwords produced by a jargon speaker, LT. Despite presenting with severe neologistic jargon, LT can produce discrete responses in picture naming tasks thus allowing the properties of his jargon to be investigated. This ability was exploited in two naming tasks. The first showed that LT's nonword errors are related to their targets despite being generally unrecognizable. This relatedness appears to be a general property of his errors suggesting that they are produced by lexical rather than nonlexical means. The second naming task used a set of stimuli controlled for their phonemic content. This allowed an investigation of target phonology at the level of individual phonemes. Nonword responses maintained the English distribution of consonants and showed a significant relationship to the target phonologies. A strong influence of phoneme frequency was identified. High frequency consonants showed a pattern of frequent but indiscriminate use. Low frequency consonants were realised less often but were largely restricted to target related contexts rarely appearing as error phonology. The findings are explained within a lexical activation network with the proposal that the resting levels of phoneme nodes are frequency sensitive. Predictions for the recovery of jargon aphasia and suggestions for future investigations are made.     

A dynamic phonological model derived from the intonational analysis of a jargon aphasic patient

This study is a detailed phonological and intonational analysis of one subject's jargon productions. The cohesiveness and complexity of the intonation patterns and appropriateness of the gestures lead to the hypothesis that the jargon productions are due to phonological problems as opposed to semantic or syntactic problems. A psycholinguistic model containing a dynamic phonological component is hypothesized to account for this subject's jargon.     

An investigation of repetition and language processing in a case of conduction aphasia

A study is reported of a single case of conduction aphasia. A battery of tasks designed to investigate the parameters of the patient's severe repetition deficit is supplemented by tests of several language functions. The results provide extensive information on a wide range of the patient's language abilities and are used to evaluate the adequacy of four models that have been offered to account for conduction aphasia. An argument is made in support of the suggestion that the syndrome of conduction aphasia should be divided into two subgroups based on patients' ability to select and realize phonemes in speech output. It is concluded that the best explanation for the disorder of patients with repetition deficit but without significant speech output problems is the hypothesis that repetition ability is compromised by a pathological limitation of auditory-verbal short-term memory. This hypothesis is extended to account for the pattern of results obtained in the language tasks.     

The relationship between phonological and morphological deficits in Broca's aphasia: further evidence from errors in verb inflection

A previous study of 10 patients with Broca's aphasia demonstrated that the advantage for producing the past tense of irregular over regular verbs exhibited by these patients was eliminated when the two sets of past-tense forms were matched for phonological complexity (Bird, Lambon Ralph, Seidenberg, McClelland, & Patterson, 2003). The interpretation given was that a generalised phonological impairment was central to the patients' language deficits, including their poor performance on regular past tense verbs. The current paper provides further evidence in favour of this hypothesis, on the basis of a detailed analysis of the errors produced by these same 10 patients in reading, repetition, and sentence completion for a large number of regular, irregular, and nonce verbs. The patients' predominant error types in all tasks and for all verb types were close and distant phonologically related responses. The balance between close and distant errors varied along three continua: the severity of the patient (more distant errors produced by the more severely impaired patients); the difficulty of the task (more distant errors in sentence completion>reading>repetition); the difficulty of the item (more distant errors for novel word forms than real verbs). A position analysis for these phonologically related errors revealed that vowels were most likely to be preserved and that consonant onsets and offsets were equally likely to be incorrect. Critically, the patients' errors exhibited a strong tendency to simplify the phonological form of the target. These results are consistent with the notion that the patients' relatively greater difficulty with regular past tenses reflects a phonological impairment that is sensitive to the complexity of spoken forms.     

The role of prosody and long-term phonological knowledge in Japanese children's nonword repetition performance

This study investigated the effects of association values and the influences of prosodic information on Japanese children's repetition of nonwords with varying association values and with or without pitch accent. Fifteen 3- and 4-year-olds (mean age = 4.42 years, range: 3.9–4.9) and nineteen 5- and 6-year-olds (mean age = 5.71 years, range: 5.1–6.1) participated in this experiment. Concerning the nonword repetition scores, an effect of association value was found only in older children for consonants of nonwords only, whereas the effect of accent pattern was observed only in young children for both consonants and vowels of nonwords. The occurrences of both effects were connected to differences in the ages of the children and the types of phoneme in nonwords. We interpret these results in the context of the framework of phonological working memory.     

Intensive training of phonological skills in progressive aphasia: a model of brain plasticity in neurodegenerative disease

Three patients with a typical syndrome of nonfluent primary progressive aphasia (Mesulam's syndrome) were trained daily with a remediation protocol including auditory exercises specifically designed to involve several aspects of phonological processing, a domain known to be specifically affected in the condition. The speech content of the exercises was based on the temporal theory of phonological processes according to which increasing the duration of formant transition should facilitate phoneme discrimination and phoneomic awareness. Significantly improved performance on the trained tasks was demonstrated in the three patients. Improvement further generalized to other tasks such as nonword repetition and reading. We conclude that such results (1) argue for using intensive focused therapy of language impairment in neurodegenerative disorders, (2) may constitute a good model of brain plasticity in neurodegenerative disorders in general, and (3) support theories of phonological processing emphasizing temporal features of the auditory signal.     

The linguistic interpretation of aphasic syndromes: Agrammatism in Broca's aphasia,an example

One of the most striking characteristics typical of the speech of Broca's aphasics is its agrammatism — the omission of ‘function’ words and inflectional morphemes. Agrammatism is generally viewed as being symptomatic of a syntactic deficit. We argue here that such an account lacks grammatical systematicity, and that the only uniform and systematic interpretation of this deficit is in terms of phonological structure. A natural class consisting of ‘function’ words and some bound morphemes can be defined with reference to the junctural properties of sentences which characterize phonological words. It is this class of elements which tend to be omitted in agrammatic speech. The goal of this paper is not only to provide an hypothesis for the interpretation of one aphasic syndrome, but also to test and illustrate the efficacy of paying close attention to substantive universals of grammatical structure in proposing accounts of linguistic deficits.     

Dissociations and associations of performance in syntactic comprehension in aphasia and their implications for the nature of aphasic deficits

Sixty-one pwa were tested on syntactic comprehension in three tasks: sentence-picture matching, sentence-picture matching with auditory moving window presentation, and object manipulation. There were significant correlations of performances on sentences across tasks. First factors on which all sentence types loaded in unrotated factor analyses accounted for most of the variance in each task. Dissociations in performance between sentence types that differed minimally in their syntactic structures were not consistent across tasks. These results replicate previous results with smaller samples and provide important validation of basic aspects of aphasic performance in this area of language processing. They point to the role of a reduction in processing resources and of the interaction of task demands and parsing and interpretive abilities in the genesis of patient performance.     

Spoken-word processing in aphasia: effects of item overlap and item repetition

Two studies were carried out to investigate the effects of presentation of primes showing partial (word-initial) or full overlap on processing of spoken target words. The first study investigated whether time compression would interfere with lexical processing so as to elicit aphasic-like performance in non-brain-damaged subjects. The second study was designed to compare effects of item overlap and item repetition in aphasic patients of different diagnostic types. Time compression did not interfere with lexical deactivation for the non-brain-damaged subjects. Furthermore, all aphasic patients showed immediate inhibition of co-activated candidates. These combined results show that deactivation is a fast process. Repetition effects, however, seem to arise only at the longer term in aphasic patients. Importantly, poor performance on diagnostic verbal STM tasks was shown to be related to lexical decision performance in both overlap and repetition conditions, which suggests a common underlying deficit.     

Stress assignment in aphasia: word and non-word reading and non-word repetition

This paper investigates stress assignment in Dutch aphasic patients in non-word repetition, as well as in real-word and non-word reading. Performance on the non-word reading task was similar for the aphasic patients and the control group, as mainly regular stress was assigned to the targets. However, there were group differences on the real-word reading and non-word repetition tasks. Unlike the non-brain-damaged group, the patients showed a strong regularization tendency in their repetition of irregular patterns. The patients' stress error patterns suggest an impairment in retention or retrieval of targets with irregular stress patterns. Limited verbal short-term memory is proposed as a possible underlying cause for the stress difficulties.     

The performance feedback process: A preliminary model

Informal performance feedback from supervisors can have a significant and generally desirable impact on the performance and job-related attitudes of their subordinates. A model of the overall feedback process is outlined. The model is concerned with the factors that influence supervisors' performance feedback behavior, as well as with the effects that giving feedback can have on both the subordinate and the supervisor him/herself. Empirical evidence bearing on this model is reviewed, and several of the model's major implications are discussed.     

Syntactic priming effects in aphasia: an investigation of local syntactic dependencies

This study explored on-line processing of local syntactic dependencies in normal subjects and in Broca's and Wernicke's aphasics using a lexical decision paradigm. In addition, subjects performed a grammatically judgement task on the real word pairs used in the lexical decision tasks. Results of two experiments for normal subjects indicated different syntactic priming effects as a function of the type of local syntactic dependency. Word pairs that formed a single constituent phrase, i.e., a verb phrase, showed both facilitory and inhibitory effects, whereas word pairs that reflected local syntactic dependencies across a phrase boundary, i.e., pronoun verb, showed only inhibitory effects. Broca's aphasics failed to show facilitory effects when presented with word pairs forming a single constituent phrase but, similar to normals, did show inhibition when presented with word pairs that reflected local syntactic dependencies across a phrase boundary. In contrast, Wernicke's aphasics failed to show inhibitory effects in both experiments. The implications of these results for theories of language processing deficits in aphasia are considered.     

Team tenure and team performance: A meta-analysis and process model

Team tenure is a key component of models of team effectiveness. However, the nature of the relationship between team tenure and team performance is unclear due to underdeveloped theory on the nature of team tenure, various unintegrated theoretical conceptualizations of team tenure, and mixed empirical findings. Further, there is a lack of theory as to the intervening team processes and emergent states that account for the “black box” of the team tenure–team performance relationship. Accordingly, we conducted meta-analyses of the relationships of team tenure with team processes and performance. Our results, based on 622 effect sizes reported in 169 studies, show that team tenure, conceptualized as additive team tenure, collective team tenure, and team tenure dispersion, is positively related to team performance. Relative weights analysis found additive team tenure to be a relatively more important predictor of team performance than collective team tenure or team tenure dispersion. We found that team cognition, motivational-affective states, and behavioral processes mediate the relationships of additive team tenure, collective team tenure, and team tenure dispersion with team performance, respectively. We discuss the implications of these findings for research and practice.     

The frequency of simultaneous disfluency and phonological errors in children: A preliminary investigation

The frequency of simultaneous disfluency and phonological errors was examined in seven young English-speaking children exhibiting coexisting stuttering and phonological disorders. Data were gathered during 30 minutes of mother-child conversation and analyzed in three parts: (1) stuttering, (2) phonological errors, and (3) stuttering and phonological error co-occurrence. Results indicated that stuttering did not occur more frequently on syllables with phonological errors than on syllables without phonological errors. However, the frequency of disfluency on word-initial consonant clusters with phonological errors was significantly higher than on word-initial consonant clusters without phonological errors. Theoretical and clinical implications are discussed.