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Syntactic Processing in Sentence Comprehension Under Dual-task Conditions in Aphasic Patients
Abstract
The functional architecture of the verbal processing resource system was studied by testing aphasic patients for their abilities to use syntactic structure in sentence comprehension in isolation and under dual-task conditions. Patients who showed evidence for a reduction in the resources available for syntactic processing in sentence comprehension were tested on a sentence-picture matching task that required syntactic processing in an o-interference condition and while recalling a series of digits that was one less than or equal to their span. Patients showed equivalent effects of syntactic complexity in comprehension in the three conditions; that is, the effect of syntactic complexity did not increase under digit load conditions. This result supports the conclusion that the processing resource system that underlies syntactic processing is substantially separate from the one that is used for some other verbally mediated functions.
... There are several types of attention, including sustained attention or vigilance (the ability to maintain focus on specific stimuli during continuous activity), selective or focused attention (the ability to respond only to specific stimuli and not respond to others), alternating or switching attention (the ability to shift focus back and forth between two or more stimuli), and divided attention (the ability to process two or more stimuli or tasks simultaneously) (Blanchet, 2016;Burda et al., 2018;Lezak et al., 2012). Previous research has indicated that all of these processes can be disrupted in PWA (Caplan & Waters, 1994;Erickson et al., 1996;Hunting-Pompon et al., 2011;Lapointe & Erickson, 1991;Laures, 2005;Murray et al., 1997Murray et al., , 1998Schumacher et al., 2019;Villard & Kiran, 2018). ...
... PWA demonstrated the most pronounced impairments in switching between letters and numbers, and in connecting letters (Schumacher et al., 2019). Other studies (Caplan & Waters, 1994;Lapointe & Erickson, 1991;Murray et al., 1998) have also shown significant differences between PWA and controls when switching between two tasks was required. In these studies, participants had to perform a verbal task (syntactic processing/picture-description task/monitoring for spoken words) and a nonverbal task (identifying tones/recalling a series of digits) at the same time. ...
... Therefore, it seems that a better way to study switching attention would be to use a task with a single category of stimuli (preferably nonverbal) in which participants have to switch their attention from one feature of an object to another. Another limitation of the current literature is that in the vast majority of studies, PWA were studied as a uniform group, with some studies just providing information about which participants had what type of aphasia (e.g., Schumacher et al., 2019;Villard & Kiran, 2018), others not even providing that information in the participant description (e.g., Caplan & Waters, 1994;Lapointe & Erickson, 1991), while others focused specifically on comparing one type of aphasia, for example, non-fluent or anomic aphasia, with controls (e.g., Erickson et al., 1996;Hunting-Pompon et al., 2011) rather than being divided according to different aphasia types or brain lesion sites. It would be useful to contrast performance on attention tasks across different types of aphasia, with an appropriate number of participants in each group, as depending on impairment profile and lesion site different mechanisms might come into play. ...
Background: Previous studies have shown that individuals with
aphasia have impairments in switching attention compared to
healthy controls. However, there is insufficient information about
the characteristics of switching attention within one task and
whether attention deficits vary depending on aphasia type and
lesion location. We aimed to address these knowledge gaps by
investigating characteristics of switching attention within one
type of task in participants with different types of aphasia and
distinct lesion sites.
Method: Forty individuals with post-stroke aphasia (20 with nonfluent
aphasia and frontal lobe damage, and 20 with fluent aphasia
and temporal lobe damage) and 20 neurologically healthy agematched
individuals performed an attention switching task. They
listened to sequences of high-pitched and low-pitched tones that
were presented to them one by one, tallied them separately, and, at
the end of each sequence, had to say how many high- and lowpitched
tones they had heard.
Results: Participants with aphasia performed significantly worse on
the task compared to healthy controls, and the performance of two
aphasia groups also differed. Specifically, individuals with both
aphasia types made more errors than healthy individuals, and the
participants with non-fluent aphasia responded more slowly than
controls, while reaction times of the participants with fluent aphasia
did not differ significantly from those of controls. Also, the two
groups of participants with aphasia differed significantly in accuracy,
with individuals in the non-fluent group making more errors.
Conclusions: The data demonstrated that people with different
types of aphasia have distinct impairments in switching attention.
Since cognitive deficits impact language performance, this information
is important for differentially addressing their language problems
and selecting more specific and optimal rehabilitation
programs that target different underlying mechanisms.
... Controversy also persists over whether there is a separate resource pool dedicated to syntactic processes (Caplan e t al. 1985, Caplan and Waters 1994, Waters and Caplan 1994, or whether there is a single resource pool dedicated to language comprehension processes in general (Carpenter e t al. 1994, Just and Carpenter 1992. Although our secondary task did not involve overt language processes, the resources upon which it was dependent overlapped at least partially with those used to complete the grammaticality judgement task. ...
... Controversy also persists over whether there is a separate resource pool dedicated to syntactic processes (Caplan e t al. 1985, Caplan and Waters 1994, Waters and Caplan 1994, or whether there is a single resource pool dedicated to language comprehension processes in general (Carpenter e t al. 1994, Just and Carpenter 1992. Although our secondary task did not involve overt language processes, the resources upon which it was dependent overlapped at least partially with those used to complete the grammaticality judgement task. ...
... Therefore, in contrast to colleagues' findings (e.g. Caplan andCaplan 1994), our results suggest that there exists another resource pool upon which syntactic processes (at least those which are used to make grammaticality judgements) may draw; whether this other resource pool is one committed to language comprehension as Carpenter and colleagues submit (e.g. Carpenter eta/. ...
This study examined the grammaticality judgements of mildly aphasic individuals under dual-task conditions in order to examine the relationship between syntactic processing and resource capacity and allocation in aphasia. Individuals with aphasia and age-matched control subjects performed a listening task that required grammaticality judgements under isolation, focused attention, and divided attention conditions. Subjects were also required to rate task difficulty following completion of each listening condition. Although grammatical sensitivity was similar between groups during the isolation condition, introduction of a secondary, competing task resulted in significantly greater dual-task interference for the aphasic than for the control subjects. Despite these group differences in dual-task performance, aphasic and control subjects' perceptions of task difficulty failed to differ significantly. These findings provide further support for a resource limitation model of syntactic processing deficits in aphasia.
... Двойные задачи часто используются для исследования разных свойств внимания при афазии (в первую очередь, эффективности переключения и распределения внимания). В данных исследованиях [Caplan, Waters, 1994;LaPointe, Erickson, 1991;Murray et al., 1998;Slansky, McNeil, 1997;Hula, McNeil, 2008] испытуемые должны были одновременно выполнять какую-то вербальную задачу (чтение / семантическую оценку / вычленение определенного вербального стимула) и невербальную (распознание тоновых стимулов / сортировку карточек / счет). В качестве зависимой переменной в подобных работах обычно выступают скорость реакции или количество ошибок. ...
... Испытуемые с афазией допускали значимо больше ошибок (ложных тревог и пропусков) и значимо реже давали правильные ответы по сравнению с группой нормы вне зависимости от частотности предъявления стимулов. Данные результаты подтверждают выдвинутую гипотезу о наличии дефицита внимания при афазии и согласуются со многими предыдущими исследованиями концентрации внимания у этой группы больных [Glosser, Goodglass, 1990;Korda, Douglas, 1997;Robin, Rizzo, 1989;Caplan, Waters, 1994;LaPointe, Erickson, 1991;Murray et al., 1998;Slansky, McNeil, 1997]. ...
Данное исследование было направлено на изучение особенностей концентрации внимания у больных с передними и задними формами афазии. Был проведен количественный и качественный анализ имеющихся у больных афазией нарушений, который заключался в их сравнении со здоровыми испытуемыми и между собой. Исследование проведено на 47 пациентах в возрасте от 24 до 75 лет, группу нормы составили 39 испытуемых сопоставимого возраста. В результате исследования были продемонстрированы особенности нарушения внимания у больных с афазией, а также была выявлена разница в характере ошибок и скорости реакции на стимулы между разными категориями больных по сравнению с группой нормы. Важность исследования функции внимания заключается в возможности применения новых данных на практике, при реабилитации больных афазией.
... Syntactic processing is one stage of the entire language com prehension process: some of the other kinds of operations in the process are acousticphonetic conversion, lexical access, intonational co n to u r recognition, sem antic and pragmatic processing, which norm ally act in a cooperative way ( Marslen-Wilson 1987). Considering that the language comprehension process is integrative in nature and is highly practised in hum an cognitive functions, Caplan & Waters hypothesised that "one resource system is utilised by all these different types of processes that combine in the interpretation process" (Caplan & Waters 1996b;Waters & Caplan 1996). ...
This thesis investigates the various syntactic sources of difficulty or ease in processing Japanese sentences. The investigation utilises the theory of Word Grammar (Hudson 1984, 1990), within which dependency distance has been developed in order to measure syntactic difficulty. My main contention is that dependency distance is just one source of difficulty, so I argue against the common idea that syntactic difficulty equals syntactic complexity and that difficulty has a single syntactic explanation. After presenting the nature of syntactic difficulty and complexity and techniques of measuring syntactic difficulty in the first chapter, in the second chapter recent theories accounting for syntactic difficulty are reviewed. The third chapter outlines a model of a parser based on Word Grammar along with dependency distance. In the fourth chapter the status of 'words' in Japanese is discussed within the framework of Word Grammar, which seeks to express syntactic knowledge in terms of direct relationships between words, so as to resolve the special problem of function words that Japanese raises. The following two chapters provide preliminary experimental data. In the fifth chapter the first experiment tentatively shows serial order effect, word-length effect, chunking effect and the contribution of function words to working memory load. The experiments in the sixth chapter tentatively show that dependency distance has a positive relationship with memorability on immediate recall tasks and "chaining" and "overload" effects. The data in the seventh chapter gives experimental evidence tentatively showing the appropriateness of measuring dependency distance for Japanese in terms of morpheme as well as "head" effects and effects of word order. Spoken English and Japanese texts are analysed in the eighth chapter to make a comparison of the syntactic difficulty amongst the texts, in which the results tentatively show that in terms of dependency distance Japanese is no more difficult for syntactic processing than English.
... Испытуемые с афазией допускали значимо больше ошибок (ложных тревог и пропусков) и значимо реже давали правильные ответы по сравнению с группой нормы вне зависимости от частотности предъявления стимулов. Данные результаты подтверждают выдвинутую гипотезу о наличии дефицита внимания при афазии и согласуются со многими предыдущими исследованиями концентрации внимания у этой группы больных [Glosser, Goodglass, 1990;Korda, Douglas, 1997;Robin, Rizzo, 1989;Caplan, Waters, 1994;LaPointe, Erickson, 1991;Murray et al., 1998;Slansky, McNeil, 1997]. ...
Features of focused attention in patients with fluent and non-fluent aphasia were investigated in the study. Attention disorders in patients with aphasia were quantitatively and qualitatively analyzed by making inter-comparison and comparing against the same disorders in healthy individuals. Forty seven patients with different forms of aphasia (aged 24–75) and thirty nine neurologically intact subjects of equivalent age (control group) took part in the study. The subjects were asked to monitor long strings of aurally presented digits and react to specific combination of two numbers. Overall, the number of correct responses was greater and reaction times were shorter in healthy subjects than in subjects with aphasia. The following differences in type of errors and reaction times between participants with fluent and non-fluent aphasia were demonstrated: subjects with fluent aphasia had lower reaction times in case of high-frequency target stimuli presentation, while subjects with non-fluent aphasia demonstrated more correct responses in case of low-frequency target stimuli presentation. Additionally, subjects with non-fluent aphasia made more errors related to omitting when one target stimulus immediately followed another. No linear relationship was found between severity of language impairment and observed focused attention deficits. Thus, the presented study demonstrates the importance of studying attention deficits in patients with aphasia in rehabilitation practice.
http://psystudy.ru/index.php/eng/2014v7n34e/968-kuptsova34e
... Working memory is acknowledged by many experts as a crucial factor in language comprehension (Caplan & Waters, 1999;Just & Carpenter, 1992), but opinions differ as to the exact nature of this cognitive resource. An older theory developed by Baddeley divided WM into a language-centric 'phonological loop' and a 'visuo-spatial scratchpad', which are connected by a central executive process (Caplan & Waters, 1996). Currently, the psycholinguistic community is divided as to whether VWM is even further segmented into separate resources for different types of linguistic processing, or whether WM is one united cognitive resource from which all processes draw. ...
... Caplan and Waters have compared the effects of the syntactic complexity and those of the concurrent memory load across clinical groups to demonstrate the separate verbal WM components between these two types of processing. Caplan and Waters (1996) investigated whether the performance of PWA on a sentence-picture matching task is affected by the concurrent digit load. They predicted that performance on the sentence comprehension task would not be affected by concurrent digit load in PWA as a function of the syntactic complexity, however, the number of propositions in sentence comprehension would be affected by the concurrent digit load; the type of task that taps into post-interpretive processing. ...
... Consequently, the memory has usually been considered a device to be employed consciously for the retrieval of information (Cassino et al., 2007). Not all stored information, however, is necessarily processed or retrieved consciously (Caplan & Walter, 1996). The retrieval or the processes of information acquisition themselves often take place implicitly and incidentally, with no conscious awareness (Reber, 1992;Seger, 1994). ...
... Arguing against the unitary nature of WM for language processing, Caplan and Waters (1996, 2004 stated that a distinct and independent module within the general verbal WM, called the "separate sentence interpretation resource", was responsible for syntactic processing. According to their account, damage to this module leads to depletion of processing resources necessary for on-line syntactic analysis, thereby causing syntactic comprehension deficits in people with aphasia . ...
... Consequently, the memory has usually been considered a device to be employed consciously for the retrieval of information (Cassino et al., 2007). Not all stored information, however, is necessarily processed or retrieved consciously (Caplan & Walter, 1996). The retrieval or the processes of information acquisition themselves often take place implicitly and incidentally, with no conscious awareness (Reber, 1992;Seger, 1994). ...
This review investigates how the unconscious information processing can create satisfactory learning outcomes, and can be used to ameliorate the challenges of teaching students to regulate their learning processes. The search for the ideal model of human information processing as regards achievement of teaching and learning objectives is a recurring issue in educational studies. Although conscious processes are more conducive to the objectives than unconscious processes, they do not necessarily result in satisfactory learning of instructional messages. Studies reviewed here show that the unconscious can play a facilitatory role in the encoding, storage, retrieval processes of information and learning activities, even when the conscious fails to achieve this. To take advantages of both conscious and unconscious processes, relevant literature suggests educators utilizing visual teaching aids that optimize use of working memory capacity and allow students to form mental imageries, thereby facilitating the comprehension of instructional messages
... Current models however describe syntactic working memory as working implicitly and independent from conscious rehearsal (Caplan & Waters, 1999). The claim is motivated by a dual-task study in which ten agrammatic participants undertook a sentence-picture matching task and a digit recall task at the same time (Caplan & Walters, 1996). While the participants' performance deteriorated with increasing sentence complexity, the additional memory load introduced by the digit recall task had no effect on the performance. ...
This thesis investigates syntactic processing in healthy adults and people with severe aphasia. In particular, it looks at two types of structural representation: The processing of linear strings, and of hierarchies generated by recursive phrase-structure rules. Both are assumed to be relevant to human syntax, although theories differ in the role assigned to each. The thesis looks at evidence from artificial grammar learning (AGL), a paradigm which investigates spontaneous syntactic processing of stimulus strings.
It has been proposed that speakers are biased towards detecting and applying recursive rules in AGL. The thesis reviews the evidence for this claim and explores syntactic processing in a series of new experiments using four different types of string structures. In contrast to previous studies, data analysis was conducted not only at the level of the group, but also explored individual behaviour and group heterogeneity. Participants did not show any evidence of applying recursive phrasestructure rules. Instead, they spontaneously detected local dependencies (which stimuli appear together and where) in a string. In addition, some participants also kept track of the number of stimuli that appeared. AGL behaviour appeared to be similar across sensory modalities, though participants made faster decisions in the visual modality.
AGL was also investigated in six people with severe aphasia. It was found that in contrast to healthy controls, two of the cases showed very atypical decision patterns. While they kept track of numerosity, they did not spontaneously detect any local dependencies. A third aphasic participant showed the same bias to a lesser degree. One case with global aphasia showed normal AGL behaviour, hinting at intact pattern processing obstructed by damaged lexical-semantic networks. It was concluded that if AGL is an indicator for natural syntactic processing, current results support theories which are primarily based on linear, instead of hierarchical, representation of structures. Further, a disruption of processes involved in linear representation might underlie agrammatism in aphasia.
... In language acquisition, fine motor control may account for timing differences (Bonvillian, Orlansky, & Novack, 1983;Petitto & Marentette, 1991). In neuropsychological impairments, deficits in general cognitive resources might obscure underlying uniformity (Caplan, 1996;Caplan & Waters, 1995;Caplan, Waters, DeDe, Michaud, & Reddy, 2007). Apparent differences in difficulty could stem from people's typical failure to create as much representational detail after listening as before speaking, even though such detail is achievable (Bock, Dell, Chang, & Onishi, 2007;Kempen et al., 2012). ...
Structural priming creates structural persistence. That is, differences in experience with syntax can change subsequent language performance, and the changes can be observed in both language production and comprehension. However, the effects in comprehension and production appear to differ. In comprehension, persistence is typically found when the verbs are the same in primes and targets; in production, persistence occurs without verb overlap. The contrast suggests a theoretically important hypothesis: parsing in comprehension is lexically driven while formulation in production is structurally driven. A major weakness in this hypothesis about comprehension-production differences is that its empirical motivation rests on the outcomes of experiments in which the priming manipulations differ, the primed sentence structures differ, and the measures of priming differ. To sharpen the comparison, we examined structural persistence with and without verb overlap in both reading comprehension and spoken production, using the same prime presentation procedure, the same syntactic structures, the same sentences, and the same participants. These methods yielded abstract structural persistence in comprehension as well as production. A measure of the strength of persistence revealed significant effects of priming and verb overlap without significant comprehension—production differences. This argues for uniformity in the structural mechanisms of language processing.
... Other studies employing dual tasks to investigate attentional mechanisms in people with aphasia have found greater interference in dual-task conditions for people with aphasia than non-brain-damaged controls (Caplan & Waters, 1994;LaPointe & Erickson, 1991;Murray, Holland, & Beeson, 1998). This finding has been attributed to a decrease in attentional capacity, as both tasks are effectively competing for the same limited resources. ...
Background: Emerging evidence suggests that left hemisphere damage may create an attentional bias towards stimuli initially processed in the right hemisphere.Aims: The current study aimed to investigate whether this hemispheric attentional bias influences spoken word production in a picture–word interference task.Methods & Procedures: Two participants with aphasia and seven healthy controls named centrally presented pictures that were preceded by a distractor word which appeared in either the left or right visual field 200 ms prior to the picture. Distractor words were semantically related, phonologically related, unrelated, or the name of the picture. Results were analysed in terms of response times and accuracy.Outcomes & Results: A greater overall facilitation effect was found in the left visual field/right hemisphere condition for both participants with aphasia, however this varied depending on distractor condition. These results are consistent with an attentional bias towards linguistic stimuli initially presented to the right hemisphere. In contrast, the results of the control group suggest a reduction in the lateralisation of language processing to the left hemisphere in healthy ageing.Conclusions: These results suggest that spoken word production may be influenced by changes in attentional mechanisms following left hemisphere damage in aphasia, as well as changes in hemispheric lateralisation and inhibition in healthy ageing. Identifying attentional conditions that optimise language performance in aphasia may have implications for new treatments in language rehabilitation.
... The left posterior middle temporal gyrus was activated more for ambiguous than unambiguous conditions, as predicted for regions subserving the retrieval of lexical-syntactic information from memory. It thus seems that the left inferior frontal cortex is crucial for syntactic processing in conjunction with the left posterior middle temporal gyrus, a finding supported by patient studies with lesions in these very same regions (Caplan and Waters, 1996;Rodd et al., 2010;Tyler et al., 2011). Presumably these regions are connected via the dorsal pathways. ...
A neurobiological model of language is discussed that overcomes the shortcomings of the classical Wernicke-Lichtheim-Geschwind model. It is based on a subdivision of language processing into three components: Memory, Unification, and Control. The functional components as well as the neurobiological underpinnings of the model are discussed. In addition, the need for extension of the model beyond the classical core regions for language is shown. The attention network and the network for inferential processing are crucial to realize language comprehension beyond single word processing and beyond decoding propositional content. It is shown that this requires the dynamic interaction between multiple brain regions.
... In normals, concurrent memory loads have not led to disproportionate increases in on-line measures of processing at syntactically demanding points in sentences compared to less demanding points . Aphasic patients with impairments of syntactically based comprehension attributable to a reduction in processing resources do not show further decrements in comprehension of syntactically complex sentences when required to retain a concurrent digit load, despite the absence of a floor effect (Caplan and Waters, 1996). These data are hard to reconcile with the view that parsing and interpretation utilize a capacity-limited store or multidimensional representations such as the CE. ...
Sixty-one people with aphasia were tested on 10 tests of short-term memory (STM) and for the ability to use syntactic structure to determine the meanings of 11 types of sentences in three tasks-object manipulation, picture matching, and picture matching with self-paced listening. Multilevel models showed relationships between measures of the ability to retain and manipulate item and order information in STM and accuracy and reaction time (RT), and a greater relationship between these STM measures and accuracy and RT for several more complex sentence types in individual tasks. There were no effects of measures of STM that reflect the use of phonological codes or rehearsal on comprehension. There was only one effect of STM measures on self-paced listening times. There were double dissociations between performance on STM and individual comprehension tasks, indicating that normal STM is not necessary to perform normally on these tasks. The results are most easily related to the view that STM plays a facilitatory role in supporting the use of the products of the comprehension process to accomplish operations related to tasks. This research was supported by NIDCD (National Institute on Deafness and Other Communication Disorders) Grant DC00942 to David Caplan.
... Although our results are consistent with the theory of Friederici (1988) about Broca's aphasia, they are also consistent with the hypothesis of a restriction in computational resources specific to morphosyntactic process (Caplan & Hildebrandt, 1988;Caplan & Waters, 1996). If normal syntactic process requires specific resources, aphasic patients should engage more of these resources to access or to maintain morphosyntactic properties of CC words (and maybe OC words) to process them fully. ...
The naming latency of a pronoun (‘he’ or ‘she’) was measured when a single previously presented name in the discourse agreed or did not agree with the pronoun. An effect of disagreement was found under conditions where participants had to judge whether the sentences were correct: pronouns that disagreed with previous names had longer naming latencies (Experiment 1). This effect was observed both in normal subjects and in aphasic patients, suggesting a preservation of the ability to immediately process a pronoun in these patients. For normal subjects, the disagreement effect was reduced but still significant when the judgement requirement was removed from the task. On the other hand, this effect was not present for aphasic patients under these conditions, suggesting a deficit of an automatic coindexation process (Experiment 3). Experiment 2 examined the effect of the number of potential antecedents on the immediate naming latency of a pronoun. The results of the three experiments are consistent with theories that assume a preservation of grammatical knowledge in aphasia despite a deficit of the on-line morphosyntactic processing of grammatical words.
... However such findings, and their significance for the relationship between the WM capacity and sentence comprehension, have been controversial for both normal and clinical populations. Some researchers have claimed that there is a single WM capacity engaged in all types of language processing (Just & Carpenter, 1992; King & Just 1991; Miyake et al., 1994), while others have argued that there are different verbal WM or short-term memory (STM) systems depending on the type of linguistic information, such as phonological, semantic, and syntactic structure (Caplan & Waters, 1999; Friedmann & Gvion, 2003; Martin et al., 2008; Waters & Caplan, 1996; Wright et al., 2007). Regardless of the hypotheses about single versus multiple WM systems, there is a common underlying assumption that the effects of WM capacity on language processing manifest themselves most evidently when the task demands are high enough to exceed WM capacity. ...
Background: Working memory (WM) has gained recent attention as a cognitive construct that may account for language comprehension deficits in persons with aphasia (PWA) (Caspari, Parkinson, LaPointe, & Katz, 1998; Martin, Kohen, & Kalinyak‐Fliszar, 2008; Wright, Downey, Gravier, Love, & Shapiro, 2007). However, few studies have investigated individual differences in performance on sentence comprehension tasks as a function of WM capacity in PWA when WM demands are manipulated.Aims: The purposes of the current study were: (1) to examine the relationships among verbal WM, sentence comprehension, and severity of impairment in PWA and (2) to investigate the differential performance of high versus low verbal WM groups on sentence comprehension tasks in which task demands were manipulated by the length of the sentence stimuli, complexity of syntactic structure, and by presentation method which varied the time over which the linguistic material was available for computation.Methods & Procedures: A total of 20 PWA were divided into high and low WM groups based on a listening version of a WM sentence span task. Each participant completed a listening version (CRTT) and three reading versions (CRTT‐R) of the Computerised Revised Token Test as the sentence comprehension tasks.Outcomes & Results: The WM task significantly predicted performance on the CRTT conditions in which information was only temporarily available, thereby imposing greater WM demands on sentence comprehension. The verbal WM task was significantly correlated with aphasia severity and a principal components analysis revealed that the WM task, overall aphasia severity, and overall reading impairment level loaded on a single factor with 76% of shared variance. The low WM group's performance was significantly lower than the high WM group on the CRTT subtests with syntactically more complex structures and on the CRTT conditions with temporally restricted presentation methods.Conclusions: This verbal WM task was significantly and moderately correlated with the overall severity of aphasia as well as with both listening and reading sentence comprehension. The WM group differences emerged only in sentence comprehension tasks with greater WM demands. These results are consistent with the notion that WM effects are most evident when WM capacity is sufficiently taxed by the task demands (e.g., Caplan & Waters, 1999; Just & Carpenter, 1992).
... However such findings, and their significance for the relationship between the WM capacity and sentence comprehension, have been controversial for both normal and clinical populations. Some researchers have claimed that there is a single WM capacity engaged in all types of language processing (Just & Carpenter, 1992; King & Just 1991; Miyake et al., 1994), while others have argued that there are different verbal WM or short-term memory (STM) systems depending on the type of linguistic information, such as phonological, semantic, and syntactic structure (Caplan & Waters, 1999; Friedmann & Gvion, 2003; Martin et al., 2008; Waters & Caplan, 1996; Wright et al., 2007). Regardless of the hypotheses about single versus multiple WM systems, there is a common underlying assumption that the effects of WM capacity on language processing manifest themselves most evidently when the task demands are high enough to exceed WM capacity. ...
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... Our study also provides evidence to support the hypothesis that temporal cycles are constrained by the same cognitive resources that are affected by dementia and the natural aging process. While we cannot say definitively which cognitive resources are affected based on the current study, our findings, considered alongside other work on aging and dementia, are consistent with the effects of limitations in executive functioning and working memory (Caplan & Waters, 1996, 1999) due to deterioration of frontal brain networks (Farag, Troiani, Bonner, Powers, Avants, et al., 2010; Gorno-Tempini, Dronkers, Rankin, et al. 2004b; Mesulam, Weineke, Rogalski, Cobia, Thompson, et al., 2009; Price, 2000). Our findings indicate that the mean of temporal cycle frequency is higher in the FTLD group as compared to the controls and it is also higher in the older controls as compared to the younger controls. ...
Spontaneous speech of healthy adults consists of alternating periods of fluent and hesitant segments, forming temporal cycles in speech fluency. The regularity of these cycles may be related to the functioning of brain networks during speech planning and execution. This paper investigates the theoretical link between human cognitive functioning and temporal cycles in speech production using a quantitative time series analysis to characterize the regularity and frequency of temporal cycles in adults with differing levels and etiology of cognitive decline. We compare spontaneous speech of adults without a neurological diagnosis, both older and younger, to that of adults with frontotemporal lobar degeneration (FTLD). Two measures of temporal cycle frequency (mean and mode) calculated from the power spectrum of speech fluency represented as a time series were found to be associated with subjects' age, regardless of diagnosis of dementia. Two measures of periodicity (g-statistic and rhythmicity-index), as well as mean frequency, differentiated between adults with and without dementia. Our study confirms the presence of regular temporal cycles in spontaneous speech and suggests that temporal cycle characteristics are affected in different ways by declines in cognitive functioning due to dementia and aging.
... due to limitations of working memory (WM) resources is not new and has been confirmed in normal (Daneman & Carpenter, 1980; Just & Carpenter, 1992; Vos, Gunter, Schriefers, & Friederici, 2001) and neurologically impaired populations (Saffran & Martin, 1990; Miyake, Carpenter, & Just, 1994; Caplan & Waters, 1995; Miyake, Carpenter & Just, 1995; Caplan & Waters, 1996; Haarmann, Just, & Carpenter, 1997) as well as in children (Crain, Shankweiler, Marcuso, & Bar- Shalom, 1990; Gaulin, & Campbell, 1994). Most proposals on the role of WM in sentence processing that are based on Baddeley & Hitch's model (1974) and its subsequent versions 1 (Baddeley, 1986, 1995, 2000) have focused on the phonological loop, but without reaching the consensus on how exactly this component contributes to sentence processing (Saffran & Martin,1990; Vallar, Basso, & Bottini,1990). ...
One question that has emerged from recent studies on sentence processing pertains to the nature of a specific cognitive mechanism implicated in maintenance of unintegrated syntactic information in ongoing sentence processing. In addition to evidence from language, recent research on musical syntax has suggested that processing of musical sequences may require a similar cognitive mechanism. In this paper evidence is discussed for the implication of syntactic working memory (SWM) in processing of language and musical syntax, arithmetic sequences, as well as in complex motor movements used with a specific expressive purpose. The idea is that an anticipatory structure-building component governs interpretation in each of these domains by processing relevant integrations within sequences of structurally dependent elements. The concept of SWM is anchored in representational modularity and the shared syntactic integration resources hypothesis, and empirically supported by neurophysiological and neuroimaging evidence.
... Third, any dual task paradigm is susceptible to misinterpretation with respect to resource theories of allocation versus, for example, " bottleneck " theories of processing; that is, a dual task decrement may occur due to response competition or the requirement to shift attention rather than capacity constraints or inefficient allocation strategies (Caplan & Waters, 1999; Murray, 1999; Shuster, 2004). Fourth, the test-retest reliability of span tasks has been questioned (Waters & Caplan, 1996), which is worrisome given the known day-to-day variability in patients with aphasia (Tseng et al., 1993). ...
Thesis (PhD) - Indiana University, Speech and Hearing, 2007 It is well known that many adults with aphasia demonstrate concomitant deficits in higher-level cognitive functions, including attention, executive function, and short-term and working memory. This has led to two premises: (a) the domain-specific hypothesis, in which aphasia is associated with additional cognitive deficits only to the extent that these are dependent upon language; and (b) the domain-general hypothesis, in which aphasia is associated with nonlinguistic cognitive impairments as a consequence of either overlapping anatomy or widespread cortical changes post-insult. The purpose of this research was to disentangle these competing hypotheses with regards to working memory (WM) in adults with aphasia. Like other categories of cognitive impairment in this patient group, past research has identified but failed to elucidate WM impairments in aphasic language processing. Toward this end, 15 adults with left-hemisphere damage and aphasia (LHD) and 12 non-brain-damaged controls (NBD) completed a parametric WM task with systematic variation of psycholinguistic complexity (high-frequency, low-frequency, or non-nameable stimuli) and WM load (0-, 1-, and 2-back). Data were analyzed with respect to the differential impact of these variables within and across subjects and groups. Whereas expected effects of word frequency were elicited in stimulus confrontation naming, LHD subjects were affected only minimally by frequency manipulations during the n-back task. Instead, these subjects demonstrated a significant performance decrement relative to controls with increasing WM load. Moreover, aphasia severity was moderately correlated with WM for non-nameable (i.e., more difficult) but not nameable stimuli. At the theoretical level, these results support a resource-based processing model in aphasia; at the neurobiological level, these findings are consistent with the proposition of widespread cortical connectivity changes irrespective of type or location of brain damage. A secondary purpose of this study was to investigate the reliability of LHD performance on the n-back task, given the known performance variability associated with aphasia and the general dearth of reliability data for higher-level tasks. Results demonstrated that the n-back task is a reliable WM indicator over time for this population.
... Another plausible explanation might be that off-line measurement in general, as in the sentence-veri cation task in the present study, is not sensitive enough to test the effect of a concurrent load on syntactic processing. This is not unlikely given that other studies using an off-line sentence-picture matching task also failed to nd an effect of concurrent load on sentence comprehension performance (Caplan & Waters, 1996;Waters, Caplan, & Rochon, 1995). Recently, Waters and Caplan (1997, p. 380) also argued that the end-of-sentenc e feature of the sentence-picture matching task might be insuf ciently sensitive to measure the effect of syntactic complexity and the interference with the concurrent load. ...
Event-related brain potentials (ERPs) and behavioural measures (reaction times and errors) were used to study the potential effects of individual differences in verbal working memory capacity (low vs. high reading span) and a concurrent verbal working memory load (low vs. high load) on the processing of sentences with a local syntactic ambiguity in German. The sentences were disambiguated at the clause-final auxiliary to either a subject relative (SR) clause or to an object relative (OR) clause. The processing difficulty for the OR as compared to the SR clauses was reflected in worse off-line comprehension performance, particularly for low span readers. Moreover, ERPs time-locked to the disambiguating auxiliary showed an early posterior positivity between 200350 ms for OR clauses as compared to SR clauses for high span readers. Low span readers, in contrast, showed a late frontal positivity between 500 and 800 ms. While the early positivity for high span readers was independent of the concurrent load, the late positivity varied as a function of concurrent load, being delayed in the high load condition. These results indicate that syntactic processes in language comprehension are related to individual differences in parsing strategies.
In this paper a general cognitive architecture of spoken language processing is specified. This is followed by an account of how this cognitive architecture is instantiated in the human brain. Both the spatial aspects of the networks for language are discussed, as well as the temporal dynamics and the underlying neurophysiology. A distinction is proposed between networks for coding/decoding linguistic information and additional networks for getting from coded meaning to speaker meaning, i.e. for making the inferences that enable the listener to understand the intentions of the speaker.
This chapter is about how attentional mechanisms influence the processing of sentences during listening and reading. It asks the question if processing a sentence costs attention. This chapter shows that attention could modulate the processing of different aspects of a sentence. Sentences are comprehended through a range of interactions with other cognitive processes like memory and attention. Different cognitive processes like memory and attention interact with different sub-levels of language such as syntax and semantics constantly, updating mental representations during sentence processing. The notion of automaticity in syntax parsing is discussed as this issue is intimately linked with attention processing.
Jake Harwood (Ph.D., Communication, University of California, Santa Barbara, 1994) is an Associate Professor of Communication and chair of the graduate program in Gerontology at the University of Arizona. He taught at the University of Kansas before moving to Tucson. His research focuses on intergroup communication with a particular focus on age groups. He is interested in how cognitive (e.g., stereotypes) and societal (e.g., mass media) representations of groups relate to communication processes. Currently, this research focuses particularly on grandparent–grandchild relationships and the ways in which those relationships are influenced by and influence attitudes concerning aging. His research draws on theories of social identity, intergroup behavior, and communication accommodation. He has published over 50 articles in professional journals. His recent publications have appeared in the Journal of Communication, Journal of Social and Personal Relationships, Communication Studies, and Communication Monographs. He is book review editor for the Journal of Language and Social Psychology, and currently serves on the editorial boards of the Journal of Communication, Communication Theory, Communication Education, and Communication Studies. He is a past chair of the Instructional and Developmental Communication Division of the International Communication Association.
Selective deficits in aphasic patients' grammatical production and comprehension are often cited as
evidence that syntactic processing is modular and localizable in discrete areas of the brain (e.g., Y.
Grodzinsky, 2000). The authors review a large body of experimental evidence suggesting that morphosyntactic
deficits can be observed in a number of aphasic and neurologically intact populations. They
present new data showing that receptive agrammatism is found not only over a range of aphasic groups,
but is also observed in neurologically intact individuals processing under stressful conditions. The
authors suggest that these data are most compatible with a domain-general account of language, one that
emphasizes the interaction of linguistic distributions with the properties of an associative processor
working under normal or suboptimal conditions.
This chapter focuses on the working memory requirement of syntactic processing. It illustrates the working memory (WM) requirements associated with syntactic processing and then documents the existence of variability in the subject's efficiency in handling the demands. The relationship is explored as well as the individual differences in WM capacity. There is a focus on research into the WM demands of syntactic processing that has capitalized on the differences in the WM demands associated with processing sentences. Another approach to the study of the functional neuroanatomy of syntactic processing in sentence comprehension has been to compare PET activity associated with processing syntactically more complex objected-extracted sentences to that associated with simpler subjectextracted sentences. Experimental controls and counterbalances were used to ensure that the two conditions differed only along the syntactic dimension.
This book offers a general introduction to reaction time research as relevant to Second Language Studies and explores a collection of tasks and paradigms that are often used in such research. It provides a lucid explanation of the technical aspects of collecting reaction time data and outlines crucial research principles and concepts that will ensure accurate data. In addition, Conducting Reaction Time Research in Second Language Studies provides step-by-step instructions for using DMDX, a software program widely used for conducting reaction time research. From general guidelines to techniques to working with data, this complete "why and how" guide for conducting reaction time research is ideal for both students/beginners and more seasoned researchers.
The current study explores the relationship between ageing, individual working memory capacity and syntactic complexity, using an immediate sentence recall task to determine whether age and working memory affect the capacity of elderly people to accurately reproduce long and short versions of center- and right-embedded object relative clauses immediately after they have been heard. The results showed no statistically significant differences between the performances of young and elderly subjects participating in the study, and suggested there is no decline in working memory capacity associated to the recall of syntactically complex sentences as part of normal ageing.
Deficits in working memory (WM) are an important subset of cognitive processing deficits associated with aphasia. However, there are serious limitations to research on WM in aphasia largely due to the lack of an established valid measure of WM impairment for this population. The aim of the current study was to address shortcomings of previous measures by developing and empirically evaluating a novel WM task with a sentence-picture matching processing component designed to circumvent confounds inherent in existing measures of WM in aphasia. The novel WM task was presented to persons with (n = 27) and without (n = 33) aphasia. Results demonstrated high concurrent validity of a novel WM task. Individuals with aphasia performed significantly worse on all conditions of the WM task compared to individuals without aphasia. Different patterns of performance across conditions were observed for the two groups. Additionally, WM capacity was significantly related to auditory comprehension abilities in individuals with mild aphasia but not those with moderate aphasia. Strengths of the novel WM task are that it allows for differential control for length versus complexity of verbal stimuli and indexing of the relative influence of each, minimizes metalinguistic requirements, enables control for complexity of processing components, allows participants to respond with simple gestures or verbally, and eliminates reading requirements. Results support the feasibility and validity of using a novel task to assess WM in individuals with and without aphasia.
Learning outcomes: Readers will be able to:
• Discuss the limitations of current working memory measures for individuals with aphasia.
• Describe how task design features of a new working memory task for people with aphasia address shortcomings of existing measures.
• Summarize the evidence supporting the validity of the novel working memory task.
Background: For many years, investigators have been exploring the reasons why there appear to be limits to human cognitive abilities. For example, it is difficult or even impossible for humans to perform several tasks simultaneously, depending on the nature of the tasks. Resource theory was developed to account for this limit. Resource theory asserts that humans possess a pool of cognitive resources that can be allocated to various cognitive tasks, but that this pool is limited. In more recent years, many aphasiologists have used resource theory to explain the mechanisms underlying the communication performance deficits of aphasia. However, there are many problems with resource theory and alternative theories exist which can better account for the limits on human cognitive abilities and for the deficits of aphasia. Aims: The first goal of this paper is to review the fundamental problems of resource theory and to describe alternative theories that can better account for the limits of human cognitive performance, especially during the simultaneous performance of two tasks. The second and primary goal of this paper is to critically evaluate studies of aphasia that have used resource theory to account for the findings and to describe how alternative theories can better account for these observations. Main Contribution: This paper provides a review and evaluation of alternative theories to resource theory, which has not been included in previous papers on aphasia and resource theory. It is important for aphasiologists to be aware of these alternative theories, so that they can critically evaluate resource theory as applied to aphasia. Conclusions: Resource theory is not a true scientific theory as defined by Popper. Aphasiologists are investing resources in testing this theory, and this distracts them from testing true scientific theories that can better account for the underlying deficits of aphasia.
Efforts to characterize the memory system that supports sentence comprehension have historically drawn extensively on short-term memory as a source of mechanisms that might apply to sentences. The focus of these efforts has changed significantly in the past decade. As a result of changes in models of short-term working memory (ST-WM) and developments in models of sentence comprehension, the effort to relate entire components of an ST-WM system, such as those in the model developed by Baddeley (Nature Reviews Neuroscience 4: 829-839, 2003) to sentence comprehension has largely been replaced by an effort to relate more specific mechanisms found in modern models of ST-WM to memory processes that support one aspect of sentence comprehension-the assignment of syntactic structure (parsing) and its use in determining sentence meaning (interpretation) during sentence comprehension. In this article, we present the historical background to recent studies of the memory mechanisms that support parsing and interpretation and review recent research into this relation. We argue that the results of this research do not converge on a set of mechanisms derived from ST-WM that apply to parsing and interpretation. We argue that the memory mechanisms supporting parsing and interpretation have features that characterize another memory system that has been postulated to account for skilled performance-long-term working memory. We propose a model of the relation of different aspects of parsing and interpretation to ST-WM and long-term working memory.
Reviews and discusses theories and research findings upon which an attentional model of aphasia is developed by first introducing attention theory and associated terminology. Literature is summarized which documents that not only may adults with aphasia present with attention deficits, but also that their attention deficits may negatively affect both their language comprehension and production skills. The clinical implications of adopting an attentional model of aphasia are considered with respect to strategies for both the assessment and treatment of adults with aphasia. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
We investigated the on-line processing of unaccusative and unergative sentences in a group of eight Greek-speaking individuals diagnosed with Broca aphasia and a group of language-unimpaired subjects used as the baseline. The processing of unaccusativity refers to the reactivation of the postverbal trace by retrieving the mnemonic representation of the verb's syntactically defined antecedent provided in the early part of the sentence. Our results demonstrate that the Broca group showed selective reactivation of the antecedent for the unaccusatives. We consider several interpretations for our data, including explanations focusing on the transitivization properties of nonactive and active voice-alternating unaccusatives, the costly procedure claimed to underlie the parsing of active nonvoice-alternating unaccusatives, and the animacy of the antecedent modulating the syntactic choices of the patients.
Caplan & Waters's neuropsychological evidence for
two types of verbal working memory rests entirely on a very restricted
definition of “syntactic complexity,” one in terms of word
order. This opens the possibility that the dissociation they observe
relates to the differential use of word-order strategies rather than
to the structure of verbal working memory.
Commentaries on our target article raise further questions
about the validity of an undifferentiated central executive that
supplies resources to all verbal tasks. Working memory tasks are
more likely to measure divided attention capacities and the efficiency
of performing tasks within specific domains than a shared resource
pool. In our response to the commentaries, we review and further
expand upon empirical findings that relate performance on working
memory tasks to sentence processing, concluding that our view that the
two are not strongly related remains viable in light of the material
presented in the commentaries. We suggest that a productive research
enterprise would be to develop the concept of working memory as a
pool of resources in relation to specific tasks.
The current study explores sentence comprehension impairments among adults following moderate closed head injury. It was hypothesized that if the factor of syntactic complexity significantly affects sentence comprehension in these patients, it would testify to the existence of syntactic processing deficit along with working-memory problems. Thirty-six adults (18 closed head injury patients and 18 healthy controls matched in age, gender, and IQ) participated in the study. A picture-sentence matching task together with various tests for memory, language, and reading abilities were used to explore whether sentence comprehension impairments exist as a result of a deficit in syntactic processing or of working-memory dysfunction. Results indicate significant impairment in sentence comprehension among adults with closed head injury compared with their non-head-injured peers. Results also reveal that closed head injury patients demonstrate considerable decline in working memory, short-term memory, and semantic knowledge. Analysis of the results shows that memory impairment and syntactic complexity contribute significantly to sentence comprehension difficulties in closed head injury patients. At the same time, the presentation mode (spoken or written language) was found to have no effect on comprehension among adults with closed head injury, and their reading abilities appear to be relatively intact.
ABSTRACT The active maintenance of working memory for sentence meaning wasin vestigated,u sing event- related brain potentials, event-related coherences, and source analysis. Participants read a
Three experiments explored the relationship between verbal working memory capacity and the comprehension of garden path sentences.
In Experiment 1, subjects with high, medium, and low working memory spans made acceptability judgments about garden path and
control sentences under whole sentence and rapid serial visual presentation (RSVP) conditions. There were no significant differences
between subjects with different working memory spans in the comprehension of garden path sentences in either condition. In
Experiments 2A and 2B, subjects with high and low working memory spans were tested on the same materials at three RSVP rates.
There were no significant differences between subjects with different working memory spans in the magnitude of the effect
of garden path sentences at any presentation rate. The results suggest that working memory capacity, as measured by the Daneman
and Carpenter (1980) reading span task, is not a major determinant of individual differences in the processing of garden path
sentences.
Patients with dementia of the Alzheimer's type (DAT) and matched normal controls were given three tests of syntactic comprehension in which nonlinguistic visual and memory task demands were varied. In all tasks, subjects were presented spoken semantically reversible sentences with a variety of syntactic structures and required to match the sentence to a picture. In the first experiment, subjects matched the spoken sentence to one of two pictures that appeared either before or immediately following the presentation of the sentence. The target picture depicted the spoken sentence correctly and the foil depicted the reversed thematic roles to those in the sentence (i.e., it was a syntactic foil). The second experiment employed a sentence video-verification task in which subjects were required to determine if the spoken sentence matched a videotaped depiction of the action in the sentence or a syntactic foil. In the third experiment, in different conditions, subjects were required to determine whether the spoken sentence matched a single picture or to choose the picture that matched the sentence from an array of two or three pictures. In this experiment, both lexical and syntactic foils were used. In all tasks, DAT patients were affected by the number of propositions in the presented sentence, but not by the syntactic complexity of the sentence. Control subjects also were unaffected by the syntactic complexity of the sentence; the number-of-proposition effect was present in some experiments in the control population. Comparison of performance across the one-, two-, and three-picture versions of the task showed that the magnitude of the effect of number of propositions increased as the number of pictures in the array increased. In addition, analysis of the data from each of the tasks separately showed that the effect of number of propositions only occurred when subjects were attempting to match the target to a syntactic foil (one-picture version) or to choose between the target and a syntactic foil (two- and three-picture versions). The results support the view that patients with DAT do not have disturbances affecting syntactic processing. In addition, they suggest that the effect of number of propositions arises at a stage of analysis that is partially separate from assigning sentence meaning, such as in holding a representation of the sentence in memory until the pictures can be analyzed and encoded and/or in comparing the results of the picture analysis with a stored representation of the sentence meaning.
Models of language comprehension have traditionally included a role for short-term or working memory to serve as a storage or computational platform to allow needed time and “computational space” for syntactic and interpretive analyses and to allow second-pass operations to repair errors in initial interpretation. In this chapter we present data from elderly adults and from individuals with neurological impairment who show good language comprehension in the face of significant reductions in memory capacity as measured by traditional span tests. We discuss current conceptions of working memory and traditional span measures in terms of language comprehension and the need for briefly sustained traces of the sensory input and the products of ongoing syntactic and semantic computations in the comprehension process.
Sentence comprehension abilities were investigated in a patient with semantic dementia who was administered tests of semantic knowledge and sentence comprehension over a 5-year period. Results showed that despite a severe and continual degradation in semantic knowledge, syntactic comprehension abilities remained largely intact. Evidence was also found for a codependency between semantics and syntax in a task in which knowledge about conceptual number influenced subject-verb agreement in the patient and in control participants. Results are discussed in relation to the nature of the sentence comprehension impairment in semantic dementia and with reference to the modularity of the components of the language processing system.
The present study examined effects of limitations in processing resources on error detection in self-produced and other-produced speech by means of a dual task paradigm. It has been suggested that error detection proceeds through perception, referred to as perceptual loop monitoring. As perceptual loop monitoring is an attentional function, it can be regarded as resource limited. In Experiment 1, subjects produced descriptions of visually presented networks, with and without simultaneously generating random sequences of finger taps. In Experiment 2, subjects detected errors in the speech of others, also with and without random generation. In both experiments a small percentage of errors was intercepted in the dual task situation, which suggest that monitoring is indeed resource limited. However, in the dual task condition of Experiment 1 errors were interrupted earlier, whereas in Experiment 2 the error detection time was delayed. The earlier interruptions in Experiment 1 could be the result of a shift to the prearticulatory monitoring channel.
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 1998. Includes bibliographical references (p. 115-122). An experiment was conducted to determine whether tests used to assess working memory in different disciplines (neuroimaging, psycholinguistics, neuropsychology) are highly correlated, and thus whether they are equivalent measures of a unitary underlying function. Scores on the different tests (N-back, reading span, backward digit span) did not correlate highly, and were predicted by measures of different hypothesized components of working memory. These results indicate that working memory is best conceived of as a system of multiple, interacting components that contribute to different aspects of task performance, rather than as a single, unified resource, and that currently popular tests of working memory cannot be used interchangeably to measure working memory. A second experiment was conducted to examine the relation between sentence memory and working memory, and to determine whether memory for sentences is a function of the number of clauses in the sentence, or the number of new discourse referents. Subjects heard sentences of different lengths (2 - 5 clauses) and structures (relative clause, sentential complement, double object). Double object sentences contained one additional discourse referent per clause than the other two sentence types. (cont.) If new discourse referents are the units of sentence memory, performance should be worse on double object sentences. If clauses are the unit of sentence memory, accuracy should be the same for all three sentence types. There were no reliable differences between double object sentences and the other two sentences types, indicating the clauses are the units of sentence memory. Subjects recalled 2-clause sentences highly accurately, and recalled 4-clause and 5-clause sentences poorly. There were large individual differences in the recall of 3-clause sentences. Over half of this variance was accounted for by individual differences in working memory. Measures of two hypothesized working memory components, the central executive and the short-term store, each accounted for independent variance in the sentence memory score. by Rose M. Roberts. Ph.D.
In dieser Arbeit wird in mehreren Experimenten untersucht, wie gut junge und alte Erwachsene Sätze mit unterschiedlich komplexer syntaktischer Struktur verstehen können. Zentrales Thema dabei sind die Schwierigkeiten, die ältere Erwachsene mit der Objekt-vor-Subjekt-Wortstellung haben. Untersucht wird, inwiefern diese beobachteten Altersunterschiede durch eine reduzierte verbale Arbeitsgedächtniskapazität der älteren Erwachsenen erklärt werden können. Dabei stellt sich die Frage, ob die Defizite ein generelles verbales Arbeitsgedächtnis betreffen oder ob es ein eigenes Verarbeitungs-system für syntaktische Informationen gibt, dessen Kapazität mit dem Alter abnimmt. Es wurde versucht, die postulierte reduzierte Arbeitsgedächtniskapazität der älteren Erwachsenen an jungen Erwachsenen zu simulieren, indem deren Arbeitsgedächtniska-pazität durch eine Zusatzaufgabe künstlich eingeschränkt wurde. Weiterhin wurden die Altersunterschiede bei syntaktisch komplexen zentraleingebetteten Relativsätzen mit denen bei syntaktisch einfacheren koordinierten Hauptsätzen verglichen. Um die Studienteilnehmer mit den seltenen objektinitialen Strukturen zu konfrontieren und ihre Erfahrung mit solchen Sätzen zu verändern, wurden schließlich sowohl junge als auch alte Erwachsene mit Sätzen mit Objekt-vor-Subjekt-Wortstellung trainiert.
For the present study, three verb roles (transitivity, thematic role, and subject-verb agreement) were investigated with individuals diagnosed with AD and FTD while using a â real-time,â also known as â on-lineâ , sentence comprehension task. It was hypothesized that AD patients would be insensitive to agreements that are semantic knowledge based (i.e., thematic) and that FTD patients would be insensitive to agreements that are grammatically based (i.e., transitivity). For the sentence task, AD (n=15), FTD (n=14), and healthy older adult control participants (n=17) were asked to listen for a target word in a sentence. Unbeknownst to participants, the target word, at times, followed an incorrect thematic, transitive, or subject-verb agreement. The control participants performed as expected on the thematic and transitive violations (i.e., it took them significantly longer to respond to a target word when it immediately followed either a transitive or thematic agreement violation compared to coherent agreement, a difference that was not evident when the target word followed the agreement by several syllables.) AD patients demonstrated the same intact processing pattern for the transitive agreement but not the thematic agreements. The FTD group and all FTD subgroups (Progressive Non-Fluent Aphasic, Semantic Dementia, and patients with an Executive Disturbance) were insensitive to both the thematic and transitive agreements. A review of performances as they relate to executive function and language tasks assisted in concluding that AD patientsâ insensitivity to thematic role knowledge may be due to degradation of the thematic role matrix in verb semantics. FTD patientsâ insensitivity to both the thematic and transitivity elements of verb knowledge may be due to a degradation of grammatical and semantic verb knowledge or processing impairments. Overall, these findings indicate that verb knowledge has separate semantic and grammatical elements that can influence sentence comprehension in patients with AD and FTD.
Ambiguity resolution is a central problem in language comprehension. Lexical and syntactic ambiguities are standardly assumed to involve different types of knowledge representations and be resolved by different mechanisms. An alternative account is provided in which both types of ambiguity derive from aspects of lexical representation and are resolved by the same processing mechanisms. Reinterpreting syntactic ambiguity resolution as a form of lexical ambiguity resolution obviates the need for special parsing principles to account for syntactic interpretation preferences, reconciles a number of apparently conflicting results concerning the roles of lexical and contextual information in sentence processing, explains differences among ambiguities in terms of ease of resolution, and provides a more unified account of language comprehension than was previously available.
The authors summarize developments in the concept of working memory as a multicomponent system, beginning by contrasting this approach with alternative uses of the term
working memory. According to a 3-component model, working memory comprises a phonological loop for manipulating and storing speech-based information and a visuospatial sketchpad that performs a similar function for visual and spatial information. Both are supervised by a central executive, which functions as an attentional control system. A simple trace-decay model of the phonological loop provides a coherent account of the effects of word length, phonemic similarity, irrelevant speech, and articulatory suppression in verbal short-term memory tasks. This model of the loop has also proved useful in the analysis of neuropsychological, developmental and, cross-cultural data. The notion of the sketchpad is supported by selective interference with imagery in normal adults and by specific neuropsychological impairment. Analysis of the central executive is illustrated by work on deficits in the ability to coordinate subproccesses in Alzheimer's disease (AD). (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Describes an approach to human performance based on economic concepts. It elaborates on the view that the human system employs utility considerations to decide on allocation of its limited resources. The efficiency of those resources for performing a task depends on parameters characterizing the task and the performer. This approach is used to discuss various models and interpretations for dual-task performance and their predictions, subject to the assumption that there is a single pool of resources. An expansion of this approach is then presented that hinges on the idea that the human-processing system incorporates a number of mechanisms, each having its own capacity. Those capacities can at any moment be allocated among several processes. Empirical evidence relevant to this idea and new interpretations for phenomena of dual-task performance suggested by it are presented. (3½ p ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Three experiments explored the relationship between verbal working memory capacity and the comprehension of garden path sentences.
In Experiment 1, subjects with high, medium, and low working memory spans made acceptability judgments about garden path and
control sentences under whole sentence and rapid serial visual presentation (RSVP) conditions. There were no significant differences
between subjects with different working memory spans in the comprehension of garden path sentences in either condition. In
Experiments 2A and 2B, subjects with high and low working memory spans were tested on the same materials at three RSVP rates.
There were no significant differences between subjects with different working memory spans in the magnitude of the effect
of garden path sentences at any presentation rate. The results suggest that working memory capacity, as measured by the Daneman
and Carpenter (1980) reading span task, is not a major determinant of individual differences in the processing of garden path
sentences.
We propose a model that explains how the working-memory capacity of a comprehender can constrain syntactic parsing and thereby affect the processing of syntactic ambiguities. The model's predictions are examined in four experiments that measure the reading times for two constructions that contain a temporary syntactic ambiguity. An example of the syntactic ambiguity is The soldiers warned about the dangers . . . ; the verb warned may either be the main verb, in which case soldiers is the agent; or the verb warned may introduce a relative clause, in which case soldiers is the patient of warned rather than the agent, as in The soldiers warned about the dangers conducted the midnight raid. The model proposes that both alternative interpretations of warned are initially activated. However, the duration for which both interpretations are maintained depends, in part, on the reader's working-memory capacity, which can be assessed by the Reading Span task (Daneman & Carpenter, 1980). The word-by-word reading times indicate that all subjects do additional processing after encountering an ambiguity, suggesting that they generate both representations. Furthermore, readers with larger working-memory capacities maintain both representations for some period of time (several words), whereas readers with smaller working-memory capacities revert to maintaining only the more likely representation.
A previous study (Baddeley et al., 1986) explored the hypothesis that patients suffering from dementia of the Alzheimer type (AD) are particularly impaired in the functioning of the central executive component of working memory. It showed that, when patients are required to perform 2 concurrent tasks simultaneously, the AD patients are particularly impaired, even when level of performance on the individual tasks is equated with that of age-matched controls. Although the results were clear, interpretation was still complicated by 2 issues: first, the question of comparability of performance on the separate tests between AD and control patients: secondly, the question of whether our results could be interpreted simply in terms of a limited general processing capacity being more taxed by more difficult dual tasks than by the individual tasks performed alone.
The present study followed up the AD and control patients after 6 and 12 mths. We were able to allow for the problem of comparability of performance by using patients as their own control. Under these conditions, there is a very clear tendency for dual task performance to deteriorate while single task performance is maintained. A second experiment varied difficulty within a single task in which patients and controls were required to categorize words as belonging to 1, 2 or 4 semantic categories. There was a clear effect of number of categories on performance and a systematic decline in performance over time. There was, however, no interaction between task difficulty as measured by number of alternatives and rate of deterioration, suggesting that the progressive deterioration in performance shown by AD patients is a function of whether single or dual task performance is required, and is not dependent on simple level of task difficulty.
Implications for the analysis of the central executive component of working memory are discus
Two experiments are reported in which age differences in working memory performance are explored. In the first study, young and older adults held 2, 3, 4, or 5 unrelated words in mind while verifying a single or complex sentence. An age-related decrement was found in subsequent serial recall of the words, and this decrement was larger with longer word lists. Experiment 2 confirmed the interaction between age and list length, using list lengths of 4, 6, and 8 words and a free-recall procedure. There was no interaction between age and divided attention in either experiment. Surprisingly, sentence complexity had a greater detrimental effect on recall in the younger group. The results are discussed in terms of articulatory rehearsal being augmented by using secondary memory in the case of younger subjects.
This study investigated the performance of young and old subjects on a modified version of the working memory task developed
by Baddeley and Hitch (1974). Subjects were required to verify a set of sentences of varying complexity while they repeated
aloud zero, two, or four words. The older subjects took longer to verify the sentences, especially when the sentences were
grammatically complex, but the effect of concurrent memory load on verification latency was the same in both groups. These
results cast doubt on the notion that there is an age-related decline in one general pool of processing resources. They also
suggest that older people have greater difficulty with the active processing aspects, rather than with the passive holding
aspects, of working memory tasks.
This study investigated age-related differences in working memory using a modified version of the Daneman and Carpenter (1980)
working memory task. The subjects were required to verify a series of sentences, and then at the end of each series recall
the final word of each sentence. Each series varied in length from one to five sentences. Performance on this task was compared
with performance in a word-alone condition, in which the subject had to remember an equivalent list of single words but without
sentence verification. When sentences of positive grammatical form were used in the sentence-span condition, age differences
were no greater than in the word alone condition; however, the age decrement increased when sentences of negative grammatical
form were used. There were no interactions between age and pacing or between age and the number of sentences in each set.
These results are discussed in relation to theories of age differences in working memory.
Sixty patients, 46 with left-hemisphere strokes and 14 with right-hemisphere strokes, and 21 normal control subjects were tested for the ability to use syntactic structures to determine the meaning of sentences. Patients enacted thematic roles (the agent, recipient and goal of an action) in 12 examples of each of 25 sentence types, which were designed to test a wide variety of syntactic operations. Both right-and left-hemisphere damaged patients performed worse than control subjects on syntactically complex sentences, and left-hemisphere patients performed worse than right-hemisphere patients. Eighteen patients with left-hemisphere strokes underwent CT scanning to image the perisylvian association cortex. There was no difference between the performance of patients with anterior and posterior lesions, and no correlation between the degree of impairment and the size of lesions in different regions of the perisylvian cortex. These results are consistent with the view that syntactic processing involves an extensive neural system, whose most important region is the left perisylvian cortex. When these results are combined with those of other studies, the picture that emerges is one in which, within this cortical region, this system manifests features of both distributed and localized processing.
The authors review M.A. Just and P.A. Carpenter's (1992) "capacity" theory of sentence comprehension and argue that the data cited by Just and Carpenter in support of the theory are unconvincing and that the theory is insufficiently developed to explain or predict observed patterns of results. The article outlines an alternative to the capacity theory, according to which the unconscious, obligatory operations involved in assigning the syntactic structure of a sentence do not use the same working memory resource as that required for conscious, controlled verbally mediated processes.
This work summarizes the empirical and theoretical work on impairments of short-term memory (often caused by damage in the left cerebral hemisphere) and contains chapters from virtually every scientist in Europe and North America working on the problem. The chapters present evidence from both normal and brain-damaged patients. Two neuropsychological issues are discussed in detail: first, the specific patterns of immediate memory impairment resulting from brain damage with reference to both multistore and the interactive-activation theoretical frameworks. Also considered is the relation between verbal STM and sentence comprehension disorders in patients with a defective immediate auditory memory: an area of major controversy in more recent years.
Linguistic analyses of aphasic patients’ performances have developed to the point where interesting, non-trivial descriptions and explanations of pathological performances are available in linguistic and processing terms. The purpose of this paper is to present a short synopsis for linguists of several recent analyses of aphasic patients’ disturbances in the sphere of comprehension of syntactic form. This presentation is designed to illustrate some of the logical and methodological issues regarding the analysis of aphasic data, as well as to present specific results of our investigations. On the basis of our case studies, we also suggest several aspects of syntactic structure and parsing.
Miyake, Carpenter, and Just (1994) present results of two sentence comprehension experiments using RSVP in normal subjects, which they say simulate important features of aphasic patients' comprehension of syntactic structures. On this basis, they claim that normal and aphasic subjects' performance represents a continuum of limitations in working memory capacity. In this paper, we argue that the Miyake et al. data do not resemble the performance of aphasic patients in crucial respects, and that their results provide evidence for the opposite conclusion…namely, that the processing resource system that underlies syntactic processing and that is affected in aphasia is substantially separate from the one used for other verbal tasks, such as reasoning and problem solving, which is tested In tasks such as the Daneman and Carpenter (1980) reading span task.
We present a case of a patient with a disorder of short-term memory. BO has a reduced span (2 to 3 items), no recency effect in free recall, and rapid forgetting in Brown-Peterson tasks, establishing her as a patient with impaired short-term verbal memory functions. She shows no effect of either phonological similarity or word length in recall of auditory or written word lists, but some recency effect under recall-from-end conditions and better performance on Brown-Peterson tasks in an unfilled than in a filled condition. This pattern of performance is interpreted as being consistent with a primary disturbance of the articulatory rehearsal processes of S.T.M. and possibly some impairment of the phonological store (using Baddeley's 1986 terminology). Her aphasic disturbance—apraxia of speech—is also consistent with a disturbance of articulatory rehearsal. BO shows a retained ability to extract phonology from print, including an ability to apply sublexical grapheme-phoneme correspondences, thus indicating that the rehearsal and transcoding functions associated with articulatory mechanisms are dissociable. Her improved performance on unfilled delays in Brown-Peterson testing, as well as her overt attempts to rehearse in this condition, also establishes a dissociation between rehearsal in span and in delayed recall tasks. BO shows excellent comprehension of a wide variety of syntactic structures with auditory, written, and speeded written presentations, indicating that articulatory rehearsal is not needed for the assignment of syntactic structure and its utilisation to establish aspects of prepositional semantics (thematic roles and co-indexation of noun phrases). BO makes errors referable to the maintenance of particular items in propositional memory systems, consistent with the view that the role of articulatory rehearsal mechanisms in sentence comprehension involves maintenance of items in an interpreted (semantic) structure.
A sentence-picture matching task was used to test the ability of patients with dementia of the Alzheimer's type (DAT) and age- and education-matched control subjects to interpret nine different sentences. These sentences differed on two dimensions…syntactic complexity and number of propositions. Subjects were tested on this task with no concurrent task (alone) and while concurrently remembering a digit load that was one less than their span or equivalent to their span. Neither group of subjects showed an effect of syntactic complexity, but DAT patients did show an effect of the number of propositions in a sentence. For all subjects, comprehension of sentences with more propositions was more greatly affected by larger digit loads, but comprehension of more complex syntactic structures was not. The performance of DAT patients was more affected than that of the control subjects on the digit task, but they were not disproportionately impaired on the sentence types which were more complex or had more propositions compared to normals. The results are discussed in relationship to the hypothesis that there is a sentence comprehension impairment in DAT that is related to the processing resource requirements of different aspects of the sentence comprehension process.
This article examines what roles, if any, working memory plays in the human capabilities to handle language. One possibility is that language comprehension is dependent upon working memory, as a consequence of the ephemeral nature of the speech input. A second is that the working memory system supports the learning of language rather than language processing per se. The article argues that in fact this is by far the most significant contribution made by working memory to the human facility with language. Individually and in concert, the subsystems of working memory play vital and highly specific roles, both in language learning in particular and in learning more generally. The article first describes the concept of working memory, and then discusses sentence processing and short-term memory, vocabulary acquisition and verbal short-term memory, and specific language impairment and working memory.
Ferreira and Clifton (1986, Experiment 1) found that readers experienced equal difficulty with temporarily ambiguous reduced relatives clauses when the first noun was animate (e.g., "The defendant examined by the lawyer was . . .") and when it was inanimate and thus an unlikely Agent (e.g., "The evidence examined . . ."). This data pattern suggested that a verb′s semantic constraints do not affect initial syntactic ambiguity resolution. We repeated the experiment using: (1) inanimate noun/verb combinations that did not easily permit a main clause continuation, (2) a baseline condition with morphologically unambiguous verbs (e.g., "stolen"), (3) a homogeneous set of disambiguating prepositional phrases, and (4) a display in which all of the critical regions were presented on the same line of text. In two eye-movement experiments, animacy had immediate effects on ambiguity resolution: only animate nouns showed clear signs of difficulty. Post-hoc regression analyses revealed that what little processing difficulty readers had with the inanimate nouns varied with the semantic fit of individual noun/verb combinations: items with strong semantic fit showed no processing difficulty compared to unambiguous controls, whereas items with weak semantic fit showed a pattern of processing difficulty which was similar to Ferreira and Clifton (1986). The results are interpreted within the framework of an evidential (constraint-based) approach to ambiguity resolution. Analyses of reading times also suggested that the millisecond per character correction for region length is problematic, especially for small scoring regions. An alternative transformation is suggested.
This article describes acquired neurogenic language disorders in terms of impairments of psycholinguistically defined processors that activate the major classes of linguistic representations in the usual tasks of language use. It contrasts this approach with traditional clinical approaches to aphasia and provides a brief description of assessment methods that can be used to identify the psycholinguistic impairments found in clients.
We report five experiments that deal with the role of verb selectional restrictions and the animacy of nouns in the construction and interpretation of syntactic structure. In the first two experiments, the effect of the selectional restriction requirements of verbs and the animacy of nouns on sentence comprehension was assessed in a speeded acceptability judgement task. Four sentence types were presented in which syntactic complexity (object vs subject relativisation) and number of propositions were orthogonally varied. Sentences contained verbs that required either animate subjects or animate objects, and unacceptable sentences were created by violating the selectional restriction requirements of the verb in the embedded clause. Analyses of both reaction time and accuracy data showed that there was an interaction between the selectional restriction requirements of verbs (which correlated perfectly with the animacy of nouns in subject or object position), and syntactic form, on these judgments.
We present the case of an aphasic patient who shows a selective impairment in interpreting syntactic structures on a test of sentence comprehension involving object manipulation. KG makes errors in assigning the antecedents of phonologically empty NPs called traces (Chomsky, 1982 a,b) in sentences like John seems to Bill to be shaving. He is significantly better at choosing the correct antecedent of another type of empty NP, namely subject- and object- controlled PRO (John persuaded Bill to shave, John promised Bill to shave). He has no trouble choosing the correct antecedents of overt pronouns and reflexives and shows no difficulty with syntactic structures that do not contain an empty category. His difficulty with trace is apparent in sentences which have a certain degree of complexity. He also misassigns the antecedent of subject-controlled PRO under one condition: when an overt reflexive or pronoun has PRO as its antecedent (John promised Bill to shave himself). The pattern of impairment suggests that KG cannot utilise one part of a parser/interpreter specifically devoted to the identification and co-indexation of empty categories when other processing demands are high, due to a specific impairment to this component, a capacity limitation, or both. The data support a theory of syntactic structure and parsing which incorporates different types of empty categories.
many claims have been made attributing comprehension deficits in brain-damaged subjects to their short-term memory deficits / however, among the patients with similar restrictions in memory span, different levels of comprehension have been found / some recent studies have demonstrated impressive sentence-processing abilities in individuals with very restricted memory spans
before dealing in detail with the empirical evidence on patients' short-term memory and comprehension abilities, this chapter addresses current theories of the comprehension process with an emphasis on the possible points at which various types of memory storage might be involved
this discussion is followed by a consideration of evidence regarding the types of memory storage that appear to be involved in typical short-term memory tasks and how these might overlap wtih those involved wtih comprehension / with this background in mind, the patterns of associations and dissociations in brain-damaged individuals will be brought to bear in determining what connections between memory and comprehension appear consistent with current evidence (PsycINFO Database Record (c) 2012 APA, all rights reserved)
series of studies were designed to examine the role of working memory and its subcomponents in written sentence comprehension (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Responds to criticisms made by E. Zurif and Y. Grodzinsky (see record
1984-26433-001) concerning a study by the present authors (see record
1984-07184-001) in which it was reported that agrammatic aphasics were able to judge the grammaticality of English sentences varying in syntactic construction. The validity of the judgment task is discussed, and Zurif and Grodzinsky's objections are refuted individually. (9 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
This paper presents a theory of syntactic comprehension disorders in aphasic patients. In line with some recent proposals, the current theory assumes that aphasic patients still possess the structural (syntactic) and procedural knowledge necessary to perform syntactic analysis. This paper, however, postulates that patients' comprehension deficits originate, at least in part, from reductions in working memory capacity for language. Based on a recently developed theory of capacity constraints in normal language comprehension (Just&Carpenter, 1992), the theory explains how reductions in working memory capacity can lead to the pattern of comprehension breakdown in aphasics, which can be characterised as a conjoint function of the patient's severity level and the structural complexity of the sentence. As supporting evidence for the theory, we report two “simulation” experiments in which we increased the computational demands on normal adults of varying working memory capacities and thereby induced in them the interaction of “severity” by complexity usually observed among aphasic patients.
The results of two experiments indicate that individual differences in syntactic processing are governed in part by the amount of working memory capacity available for language comprehension processes. Reading the verbs of an object relative sentence, such as The reporter that the senator attacked admitted the error, takes more time for readers with less working memory capacity for language, and their resulting comprehension is less accurate. Experiment 1 investigated the effects of a concurrent working memory load and found that with no load or a small memory load many Low Span readers comprehended object relative sentences very poorly although their reading times in the critical area of these sentences were greater than those of High Span subjects. Experiment 2 replicated the reading time effects of Experiment 1 for object relative sentences and showed that pragmatic information improved the comprehension of the lower capacity readers, although their use of this information was limited to the clause in which it was presented.
Working memory capacity determines how well individuals can use context to both comprehend and produce words. When required to comprehend an unfamiliar word such as spaneria, individuals with small working memories were less able to construct the meaning “scarcity of men” from cues provided by the verbal context. Working momory was assessed by the reading span test that taxes the processing and storage functions of working memory during sentence comprehension. The theory proposes that individuals with small spans devote so many resources to reading processes that they have less residual capacity for retaining the relevant contextual cues in working memory. When required to access their lexical knowledge and produce a context-appropriate replacement for a familiar word such as conflict, individuals with smaller working memories were much slower. However, working memory had to be assessed by the speaking span test that taxes the processing and storage functions of working memory during sentence production, suggesting that the functional capacity of working memory varies with the processing characteristics of the task being performed.
We present the results of three studies of aphasic comprehension of syntactic structure. Group analysis reveals effects of syntactic structure upon correct interpretation of sentences and indicates that separate aspects of syntactic structure contribute additively to sentence complexity. Identifiable subgroups of patients vary in overall ability on this task, and some subgroups show quite isolated impairments with specific sentence types. Subgroups do not correspond to classical aphasia syndromes, and lesion site does not correlate with patient subgroups. The results bear on the nature of impaired syntactic comprehension in aphasia and on aspects of the normal parser/interpreter.RésuméNous présentons les résultats de trois études sur to compréhension de la structure syntaxique par des aphasiques. L'analyse des données du groupe montre que la structure syntaxique influe sur ('interpr'etation correcte des phrases et indique que différents aspects de cette structure contribuent additivement à la complexité de la phrase. On peut identifier des sous-groupes de patients variant selon leur capacité générale à réaliser la tâche et des sous-groupes présentant des incapacités locales isolées pour des types de phrases spécifiques. Ces sous-groupes ne recouvrent pas les syndromes aphasiques classiques et ne corrèlent pas avec les sites des lésions. Les résultats mettent en jeu la nature de l'atteinte de la compréhension syntaxique dans l'aphasie et les aspects de la segmentation/interprétation normale.
Individual differences in reading comprehension may reflect differences in working memory capacity, specifically in the trade-off between its processing and storage functions. A poor reader's processes may be inefficient, so that they lessen the amount of additional information that can be maintained in working memory. A test with heavy processing and storage demands was devised to measure this trade-off. Subjects read aloud a series of sentences and then recalled the final word of each sentence. The reading span, the number of final words recalled, varied from two to five for 20 college students. This span correlated with three reading comprehension measures, including verbal SAT and tests involving fact retrieval and pronominal reference. Similar correlations were obtained with a listening span task, showing that the correlation is not specific to reading. These results were contrasted with traditional digit span and word span measures which do not correlate with comprehension.
Efficient techniques that give measures of local parsing complexity throughout sentences are needed to study the detailed course of sentence parsing. A new technique, the Continuous Lexical Decision Task, was tested to determine the whether it is sensitive to differences in local parsing complexity throughout sentences. Experiment 1 demonstrated that subjects performing the task treat sentences as sentences. Experiment 2 demonstrated that the task is sensing to on-line syntactic processing. Results showed not only that Object relatives are harder to process than Subject relatives, but also that parsing complexity is increased at the gap in Object relatives and remains increased for the next couple of words. The results suggest that the difficulty of Object relatives in comparison to Subject relatives lies in the assignment of the head as the filler of the gap.
This paper analyzes the effect on performance when several active processes compete for limited processing resources. The principles discussed show that conclusions about the interactions among psychological processes must be made with caution, and some existing assumptions may be unwarranted. When two (or more) processes use the same resources at the same time, they may both interfere with one another, neither may interfere with the other, or one may interfere with a second without any interference from the second process to the first. The important principles are that a process can be limited in its performance either by limits in the amount of available processing resources (such as memory or processing effort) or by limits in the quality of the data available to it. Competition among processes can affect a resource-limited process, but not a data-limited one. If a process continually makes preliminary results available even before it has completed all its operations, then it is possible to compute performance-resource operating characteristics that show how processes interact. A number of experiments from the psychological literature are examined according to these processing principles, resulting in some new interpretations of interactions among competing psychological processes.
A theory of the way working memory capacity constrains comprehension is proposed. The theory proposes that both processing and storage are mediated by activation and that the total amount of activation available in working memory varies among individuals. Individual differences in working memory capacity for language can account for qualitative and quantitative differences among college-age adults in several aspects of language comprehension. One aspect is syntactic modularity: The larger capacity of some individuals permits interaction among syntactic and pragmatic information, so that their syntactic processes are not informationally encapsulated. Another aspect is syntactic ambiguity: The larger capacity of some individuals permits them to maintain multiple interpretations. The theory is instantiated as a production system model in which the amount of activation available to the model affects how it adapts to the transient computational and storage demands that occur in comprehension.
Psychological theories of natural language processing have usually assumed that the sentence processor resolves local syntactic ambiguities by selecting a single analysis on the basis of structural criteria such as Frazier's (1978) "minimal attachment." According to such theories, alternative analyses will only be attempted if the initial analysis subsequently proves inconsistent with the context. (See also Ferreira & Clifton, 1986; Ford, Bresnan, & Kaplan, 1982; Rayner, Carlson, & Frazier, 1983). An alternative hypothesis exists, however: If sentences are understood incrementally, more or less word-by-word (Marlsen-Wilson, 1973, 1975), then syntactic processing can in principle exploit the fact that interpretations are available, using them "interactively" to select among alternative syntactic analyses on the basis of their plausibility with respect to the context. The present paper considers possible architectures for such incremental and interactive sentence processors, and argues for an architecture.
This study explored the hypothesis that patients suffering from dementia of the Alzheimer type (DAT) are particularly impaired in the functioning of the Central Executive component of working memory, and that this will be reflected in the capacity of patients to perform simultaneously two concurrent tasks. DAT patients, age-matched controls and young controls were required to combine performance on a tracking task with each of three concurrent tasks, articulatory suppression, simple reaction time to a tone and auditory digit span. The difficulty of the tracking task and length of digit sequence were both adjusted so as to equate performance across the three groups when the tasks were performed alone. When digit span or concurrent RT were combined with tracking, the deterioration in performance shown by the DAT patients was particularly marked.
We present the results of a study of sentence comprehension in an agrammatic patient. The patient showed striking regularities in interpreting a wide variety of sentence structures. We analyze her performance as the result of attempting to interpret a simplified syntactic structure, consisting of a linear sequence of lexical categories, according to a number of simple interpretive strategies.
The performance of young and old adults was compared in two different situations to investigate the reasons why the latter are especially poor at divided attention tasks. Although the two experimental tasks were quite different, one a single task and the other time-sharing, task difficulty was manipulated in a similar fashion in both situations. Specifically, in both tasks difficulty was varied by manipulation of number of items to be rehearsed and number of mental operations necessary for successful performance. The most salient difference in task demands, that is, divided versus nondivided attention, had little effect on results. Performance of both age groups declined as task difficulty increased, with the decline being greater and more rapid for the older subjects. Results are discussed in terms of competition for limited processing capacity in working memory.
Twenty-three early-stage dementia of the Alzheimer type (DAT) patients and twenty-three control subjects were tested on a sentence-picture matching test containing nine different sentence types representing different levels of syntactic complexity. Subjects chose between drawings depicting a target sentence and a syntactic foil. Results indicated that DAT patients differed from control subjects on four of the nine sentence types. Performance of the patients was not poorer for sentences that were syntactically more complex, but was poorer for sentences that had two propositions as compared to one. Results are discussed in terms of a post-interpretative processing impairment in sentence comprehension in DAT.
We describe three experiments that explore the real-time access of verb-argument structures in a group of normal control subjects, a group of Broca's aphasic patients, and a group of Wernicke's aphasic patients. Specifically, we examine whether our subjects exhaustively access the thematic representations of verbs in active, passive, cleft-subject, and cleft-object sentences. We find that our normal control subjects and Broca's aphasic patients are sensitive to the thematic properties of verbs, regardless of sentence type. Our Wernicke's aphasic patients do not show on-line sensitivity to this lexical property. We discuss these results in terms of multiple resources dedicated to specific sentence processing devices, a possible semantic deficit in Wernicke's aphasia, and a double-dissociation between the operation of accessing a verb's thematic properties and the operation of computing the trace-antecedent relation.