Sentence Comprehension Deficits in Alzheimer''s Disease: A Comparison of Off-Line vs. On-Line Sentence Processing

Two studies explored whether sentence comprehension impairments in Alzheimer's disease (AD) are due to deficits in syntactic processing or memory. Study 1 used a picture-pointing sentence comprehension task to measure the final outcome of comprehension in an off-line fashion. It showed the comprehension of 30 patients with AD to be impaired, but suggested that the deficits could not be attributed solely to syntactic impairments. Study 2 investigated the effects of memory on sentence comprehension by comparing off-line (grammaticality judgment) with on-line (cross-modal naming) language processing in 11 AD and 9 control subjects. The results revealed impaired performance in the off-line task but normal performance in the on-line task using the same sentences. Performance on the off-line task correlated with independent measures of verbal working memory. These data are used to argue that sentence comprehension impairments are related to verbal working memory deficits in AD.     

Listening comprehension and working memory are impaired in attention-deficit hyperactivity disorder irrespective of language impairment

This study investigated listening comprehension and working memory abilities in children with attention-deficit hyperactivity disorder (ADHD), presenting with and without language impairments (LI). A 4-group design classified a community sample (n = 77) of boys aged 9–12 into ADHD, ADHD + LI, LI, and Normal groups. Children completed tests of basic language and cognitive skills, verbal and spatial working memory, and passage-level listening comprehension. Multivariate analyses and post hoc comparisons indicated that ADHD children who did not have co-occurring LI comprehended factual information from spoken passages as well as normal children, but were poorer at comprehending inferences and monitoring comprehension of instructions. ADHD children did not differ from normal children in verbal span, but showed significantly poorer verbal working memory, spatial span, and spatial working memory. The ADHD + LI and LI groups were most impaired in listening comprehension and working memory performance, but did not differ from each other. Listening comprehension skills were significantly correlated with both verbal and spatial working memory, and parent–teacher ratings of inattention and hyperactivity/impulsivity. Findings that children with ADHD but no LI showed subtle higher-level listening comprehension deficits have implications for both current diagnostic practices and conceptualizations of ADHD.     

The contribution of apraxic speech to working memory deficits in Parkinson's disease

This article links two formerly separate areas of research associated with Parkinson's disease (PD): speech and memory. It is proposed that speech deficits occur in PD not merely at the level of muscular control, as is commonly termed dysarthria, but also at the level of speech planning and programming, more aptly described as a form of apraxia. It is further argued that PD patient groups exhibit small deficits in verbal span, and the link between apraxic speech and verbal span is elucidated via Baddeley's (1986) model of working memory. An experiment is described in which aspects of speech of 36 PD and 43 healthy control subjects were rated and classified, and measures of span and articulation rate for words of different syllable lengths were taken. Twenty-three PD subjects had dysarthric speech, while 14 of them had apraxic speech, which was associated with lower memory span scores for longer words. It is concluded that apraxic speech can be a source of reduced memory span in PD. In addition to implications for rehabilitation and therapeutic work with PD sufferers, these findings advance our theoretical understanding of the Parkinsonian syndrome.     

Effects of verbal working memory deficits on metaphor comprehension in patients with Parkinson's disease

This research studied one aspect of pragmatic language processing, the ability to understand metaphorical language, to determine whether patients with Parkinson disease (PD) are impaired for these abilities, and whether cognitive resource limitations/fronto-striatal dysfunction contributes to these deficits. Seventeen PD participants and healthy controls (HC) completed a series of neuropsychological tests and performed a metaphor comprehension task following the methods of Gernsbacher and colleagues [Gernsbacher, M. A., Keysar, B., Robertson, R. R. W., & Werner, N. K. (2001). The role of suppression and enhancement in understanding metaphors. Journal of Memory and Language, 45, 433-450.] When participants in the PD group were identified as "impaired" or "unimpaired" relative to the control group on a measure of verbal working memory span, we found that only PD participants with impaired working memory were simultaneously impaired in the processing of metaphorical language. Based on our findings we argue that certain "complex" forms of language processing such as metaphor interpretation are highly dependent on intact fronto-striatal systems for working memory which are frequently, although not always, compromised during the early course of PD.     

Assessing resource demands during sentence processing in Parkinson's disease

Patients with Parkinson's disease (PD) have sentence comprehension difficulty, but it is unclear whether this is due to a deficit in grammatical processing or to an executive resource limitation. To assess grammatical processing in PD while minimizing task-related demands, PD patients and healthy control subjects performed a word detection procedure that assesses sensitivity to grammatical agreements in sentences in an "on-line" fashion. With this technique, we found that control subjects and PD patients are equally sensitive to grammatical agreement violations in sentences. A traditional, resource-demanding measure of sentence comprehension was also administered to the same PD patients. In comparison to healthy controls, PD patients were significantly impaired in their relative comprehension of sentences containing object-gap subordinate clauses compared to subject-gap subordinate clauses. Performance on several executive resource measures was also impaired in PD, and this correlated with their comprehension performance. Sensitivity to grammatical agreements with the word detection procedure, in the context of sentence comprehension difficulty on a traditional measure, suggests that PD patients' executive resource limitations contribute to their sentence comprehension difficulty.     

Working memory as a predictor of verbal fluency

This study investigated whether working memory capacity could account for individual differences in verbal fluency. Working memory was assessed by the speaking span test (Daneman & Green, 1986) that taxes the processing and storage functions of working memory during sentence production. Verbal fluency was assessed by (1) a speech generation task in which subjects made a speech about a picture; (2) an oral reading task in which subjects read aloud a prose passage; and (3) a Baars, Motley, and MacKay (1975) task for eliciting oral slips of the tongue (e.g.,wet gun forget one). Speking span was significantly correlated with performance on all three tasks; individuals with small speaking spans were less fluent and more prone to making speech errors. Whereas speaking span was related to individual differences in verbal fluency on the speech and reading tasks, reading span, a measure included to assess working memory capacity during sentence comprehension, was only significantly related to individual differences in verbal fluency on the reading task. The methodology proved useful for revealing whether a particular kind of oral reading error reflected a reading failure or an articulatory failure.This research was supported by a grant from the Natural Sciences and Engineering Research Council of Canada.     

Knowing the meaning, getting the point, bridging the gap, and carrying the message: aspects of discourse following closed head injury in childhood and adolescence

Pragmatic communication or discourse was studied in 33 children and adolescents following closed head injury. Three-quarters of the sample was impaired on at least one of four discourse tests (knowing the alternate meanings of ambiguous words in context; getting the point of figurative or metaphoric expressions; bridging the inferential gaps between events in stereotyped social situations; and producing speech acts that express the apparent intentions of others). Resolution of ambiguity was correlated with word fluency and verbal domain knowledge, but not with object naming; understanding of metaphor was correlated with verbal domain knowledge, but not with literal sentence comprehension or with the formation of analogies; making inferences was correlated with working memory capacity but not with social knowledge; and producing speech acts was not correlated either with sentence construction or with social knowledge. These associations and dissociations reveal some of the correlates of impaired discourse processing after closed head injury in childhood and adolescence, as well as bearing on theoretical questions concerning the nature of normally developing discourse processes.     

Attentional resource and processing speed limitations during sentence processing in Parkinson's disease

Several studies have suggested that patients with Parkinson's disease (PD) have sentence comprehension difficulty in part because of their limited executive resources. However, these assessments confound the executive resources contributing to sentence comprehension with the resources needed for task performance. In the present study, we used a word detection technique that minimizes task demands in order to evaluate attentional and processing speed resources during the comprehension of simple sentences without subordinate clauses and sentences containing subject-relative and object-relative center-embedded subordinate clauses. We found that PD patients have poor sensitivity to phonetic errors embedded in unbound grammatical morphemes, regardless of the clausal structure of the sentence, suggesting difficulty attending to grammatical morphemes. We also found that PD patients are significantly slowed in their sensitivity to phonetic errors in content words embedded in object-relative center-embedded sentences. Slowed sensitivity to content words in object-relative sentences was correlated with timed executive measures of planning. On a traditional measure of comprehension, these PD patients were impaired for sentences containing object-relative center-embedded clauses compared to sentences with subject-relative center-embedded clauses, and comprehension of object-relative sentences was correlated with executive measures. Our findings are consistent with the claim that limited executive resources for strategic attention and processing speed contribute to the sentence comprehension difficulties of PD patients.     

Profile of cognitive deficits and associations with depressive symptoms and intelligence in chronic early‐onset schizophrenia patients

Cognitive deficits in several domains have been demonstrated in early‐onset schizophrenia patients but their profile and relation to depressive symptoms and intelligence need further characterization. The purpose was to characterize the profile of cognitive deficits in chronic, early‐onset schizophrenia patients, assess the potential associations with depressive symptom severity, and examine whether cognitive deficits within several domains reflect intelligence impairments. This study compared attention, visual‐construction, aspects of visual and verbal memory, and executive functions in chronic, early‐onset schizophrenia patients (mean age = 20.7 years) (N = 18) and healthy controls (N = 38). Schizophrenia diagnoses were established at the time of the patients' first clinical presentation during childhood or adolescence and were confirmed five years later. In the chronic phase of early‐onset schizophrenia, significant deficits were observed in all specific cognitive functions. The profile of cognitive deficits was jagged, and visual‐construction, attention, and one aspect of verbal memory (verbal stories recall) were differentially impaired. Deficits of visual recall, visual recognition, and executive functions were accounted for by deficits in intelligence, while this was not the case for deficits of verbal recall of stories or attention. No significant associations were observed between the severity of cognitive deficits and that of depressive symptoms. Chronic, early‐onset schizophrenia is characterized by a broad and jagged profile of cognitive deficits. Deficits of attention and verbal recall of stories appear not to be accounted for by deficits in intelligence, and the severity of cognitive deficits seems independent from that of depressive symptoms     

The uses of short-term memory: A case study

It has been widely claimed that the systems employed in tasks of immediate memory have a function in the comprehension of speech; these systems, it has been proposed, are used to hold a representation of the speech until a syntactic analysis and interpretation have been completed. Such a holding function is meant to be especially important where the sentences heard are long or complex. It has thus been predicted that subjects with impaired short-term memory performance would show deficits in comprehension of such materials.

In this study, one subject with impaired phonological processing and a severely reduced digit span was tested on a range of tasks requiring the syntactic analysis, memory and comprehension of long and complex material. She was found to be unimpaired on syntactic analysis and comprehension, but not on sentence repetition. The implications for models of short-term memory are discussed.     

言语工作记忆、句子理解与句法依存关系加工

言语工作记忆在句子理解中作用的机制和性质,是当前认知神经科学研究的一个中心课题。文章首先回顾了与支撑语言理解的工作记忆资源的性质有关的理论争论和实验证据,然后回顾了填充语-空位依存关系加工这一能够揭示言语工作记忆与句子理解之间关系的重要领域,最后简要展望了今后应该进一步研究的几个问题     

The Measurement of Verbal Working Memory Capacity and Its Relation to Reading Comprehension

Ninety-four subjects were tested on the Daneman and Carpenter (1980) reading span task, four versions of a related sentence span task in which reaction times and accuracy on sentence processing were measured along with sentence-final word recall, two number generation tasks designed to test working memory, digit span, and two shape-generation tasks designed to measure visual-spatial working memory. Forty-four subjects were retested on a subset of these measures at a 3-month interval. All subjects were tested on standard vocabulary and reading tests. Correlational analyses showed better internal consistency and test-retest reliability of the sentence span tasks than of the Daneman-Carpenter reading span task. Factor analysis showed no factor that could be related to a central verbal working memory; rotated factors suggested groupings of tests into factors that correspond to digitrelated tasks, spatial tasks, sentence processing in sentence span tasks, and recall in sentence span tasks. Correlational analyses and regression analyses showed that the sentence processing component of the sentence span tasks was the best predictor of performance on the reading test, with a small independent contribution of the recall component. The results suggest that sentence span tasks are unreliable unless measurements are made of both their sentence processing and recall components, and that the predictive value of these tasks for reading comprehension abilities lies in the overlap of operations rather than in limitations in verbal working memory that apply to both.     

Articulatory and phonological deficits in short-term memory and their relation to syntactic processing

The relationships between sentence comprehension deficits and deficits in the articulatory or phonological components of short-term memory were investigated. Nonfluent agrammatic patients showed very poor comprehension of syntax while a group of nonfluent patients who were not agrammatic showed good comprehension, despite both groups showing similar degrees of deficits in an articulatory component of memory. The results imply that a disruption of inner rehearsal has little consequence for auditory sentence comprehension, and that the syntactic comprehension deficits of the agrammatic patients could not be attributed to their memory deficit. A patient with a disruption in phonological storage showed good comprehension for many sentences, but was impaired when a difficult syntactic structure was encountered early in a sentence. It was proposed that phonological storage serves to hold words in a phonological form when sentence processing cannot keep pace with sentence input. Although a role for phonological storage was postulated, the impressive degree of syntactic processing that could be carried out by patients with very restricted memory spans implies that there is little overlap between the memory systems disrupted in these patients and the working memory system presumed to be involved in sentence comprehension.     

Impaired perception of vocal emotions in Parkinson's disease: influence of speech time processing and executive functioning

Little is known about the underlying dimensions of impaired recognition of emotional prosody that is frequently observed in patients with Parkinson's disease (PD). Because patients with PD also suffer from working memory deficits and impaired time perception, the present study examined the contribution of (a) working memory (frontal executive functioning) and (b) processing of the acoustic parameter speech rate to the perception of emotional prosody in PD. Two acoustic parameters known to be important for emotional classifications (speech duration and pitch variability) were systematically varied in prosodic utterances. Twenty patients with PD and 16 healthy controls (matched for age, sex, and IQ) participated in the study. The findings imply that (1) working memory dysfunctions and perception of emotional prosody are not independent in PD, (2) PD and healthy control subjects perceived vocal emotions categorically along two acoustic manipulation continua, and (3) patients with PD show impairments in processing of speech rate information.     

Individual differences in sentence memory

Results from an experiment with two parts are presented in this paper. In part one, participants listened to sentences containing two, three, four, or five clauses, and were asked questions about the content of the sentences. The results of part one demonstrate that an important unit of representation in sentence memory is the clause, and not some other component of discourse structure. In part two, the same group of participants performed eight different short-term storage/working memory tasks. A composite complex span score was computed for each participant based on three working memory tasks closely based on Daneman & Carpenter's (1980) reading span task. This working memory measure was significantly correlated with the participants' performance on the sentence memory task in part one. A second working memory measure—N-back—was also significantly correlated with the participants' performance on the sentence memory task, and there was no correlation between their performance on the complex span task and the N-back task. It is therefore concluded that (i) working memory consists of a number of dissociable components; and (ii) memory for sentences taps into more than one of these working memory components. Furthermore, the high correlations of sentence memory with the complex span and the N-back tasks (neither of which are language processing tasks) suggests that memory for sentences is not simply a result of linguistic experience; rather, it is likely that an independent working memory component contributes to participants' performance on the sentence memory task.     

Role of Working Memory in Typically Developing Children’s Complex Sentence Comprehension

The influence of three mechanisms of working memory (phonological short-term memory (PSTM capacity), attentional resource control/allocation, and processing speed) on children's complex (and simple) sentence comprehension was investigated. Fifty two children (6-12 years) completed a nonword repetition task (indexing PSTM), concurrent verbal processing-storage task (indexing resource control/allocation), auditory-visual reaction time (RT) task (indexing processing speed), and a sentence comprehension task that included complex and simple sentences. Correlation and regression analyses were run to determine the association between the memory variables and sentence comprehension accuracy. Results revealed: (1) none of the memory variables correlated with simple sentence comprehension, (2) resource control/allocation and processing speed correlated significantly with complex sentence comprehension, even after covarying for age, and (3) attentional functioning and processing speed predicted complex sentence comprehension (after accounting for age). Results were interpreted to suggest that working memory is significantly involved in school age children's comprehension of familiar complex sentence structures.     

Individual differences in language development: relationship with motor skill at 21 months

Language development has long been associated with motor development, particularly manual gesture. We examined a variety of motor abilities – manual gesture including symbolic, meaningless and sequential memory, oral motor control, gross and fine motor control – in 129 children aged 21 months. Language abilities were assessed and cognitive and socio‐economic measures controlled for. Oral motor control was strongly associated with language production (vocabulary and sentence complexity), with some contribution from symbolic abilities. Language comprehension, however, was associated with cognitive and socio‐economic measures. We conclude that symbolic, working memory, and mirror neuron accounts of language–motor control links are limited, but that a common neural and motor substrate for nonverbal and verbal oral movements may drive the motor–language association.     

Understanding text after severe closed-head injury: assessing inferences and memory operations with a think-aloud procedure

A think-aloud method was used to examine the content of information available to working memory during narrative comprehension in a CHI population. Twenty severe CHI participants (>1 year post-injury) and 20 controls talked aloud after they read each sentence of story narratives. Trabasso and Magliano's (1996a) verbal protocol analysis was then used to code for the production of inferential and non-inferential clauses and the memory operations that supported inferential clause production. We found that CHI and control groups produced a comparable number of clauses, that inferences dominated narrative comprehension, and that both groups produced more explanatory inferences than predictive or associative inferences. Despite these qualitative similarities, the CHI group demonstrated poorer comprehension, generated proportionately fewer inferences, relied less on retrieval as a memory source for explanatory inferences, and produced more non-inferential clauses and associative inferences.     

Neuropsychological functioning in hemiparkinsonism

A standardized neuropsychological battery including measures of intellectual cognitive, memory, attention-concentration, language, abstraction and mental flexibility, and sensory and motor functions was administered to 21 hemiparkinsonian patients (14 with right side and 7 with left side symptoms) and 17 controls matched for age and education. Patients were impaired in all functions except sensory. For motor functions, impairment was ipsilateral to the side of symptoms. For cognitive functions, right side symptoms were associated with verbal deficits whereas left side symptoms were associated with spatial deficits. Thus, a pattern of neuropsychological deficits consistent with the lateralization of motor symptoms may appear in the early stages of the disease.     

The Effects of Phonological Short-Term Memory and Speech Perception on Spoken Sentence Comprehension in Children: Simulating Deficits in an Experimental Design

The roles of phonological short-term memory (pSTM) and speech perception in spoken sentence comprehension were examined in an experimental design. Deficits in pSTM and speech perception were simulated through task demands while typically-developing children (N \(=\) 71) completed a sentence-picture matching task. Children performed the control, simulated pSTM deficit, simulated speech perception deficit, or simulated double deficit condition. On long sentences, the double deficit group had lower scores than the control and speech perception deficit groups, and the pSTM deficit group had lower scores than the control group and marginally lower scores than the speech perception deficit group. The pSTM and speech perception groups performed similarly to groups with real deficits in these areas, who completed the control condition. Overall, scores were lowest on noncanonical long sentences. Results show pSTM has a greater effect than speech perception on sentence comprehension, at least in the tasks employed here.