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Specificity of the Right Hemisphere's Contribution to Verbal Communication: The Cognitive Resources Hypothesis
Abstract
A lesion in the right cerebral hemisphere (RH) interferes with verbal communication, and specifically with the semantic processing of words. However, the reported impairments of the semantic processing of words among right-hemisphere-damaged (RHD) individuals are usually seen when the task is especially demanding, probably because this is when most processing resources are required. The goal of this article is to discuss some of the conceptual and methodological issues regarding the possible role played by cognitive resource limitations in accounting for the RH's contribution to verbal communication abilities. To this end, this article reviews the literature on the concept of cognitive resources and on their evaluation. Discussion focuses on the possibility that the RH's contribution to verbal communication abilities is, at least in part, the expression of the complementary and necessary contribution of the RH to the pool of attentional resources needed for the most effortful cognitive processing.
... Some are temporal. The resources affect each other, exist as a resource pool (Kahneman, 1973), and are necessary for cognitive processing (Monetta & Joanette, 2003). Both endogenous and exogenous resources are necessary to battle the dark side of IT. ...
... And older adults (commonly called 'silver surfers') are also taking advantage of access to the Internet and smartphones so that they can be in a state of constant communication with others (Colbert et al., 2016). One study even reported that it is parents, not teenagers or tweens, who spend the most time in front of screens (Molina, 2017). ...
... In Hawaii, 'smartphone zombies', or pedestrians so distracted by what's on their phones that they are oblivious when crossing streets, are fined. Further, 47 states and the District of Columbia have banned texting while driving (Molina, 2017). ...
We live in a world of limitless information. With technology advancing at an astonishingly fast pace, we are challenged to adapt to robotics and automated systems that threaten to replace us. Both at home and at work, an endless range of devices and Information Technology (IT) systems place demands upon our attention that human beings have never experienced before, but are our brains capable of processing it all? In this important new book, an in-depth view is taken of IT's under-studied dark side and its dire consequences on individuals, organizations, and society. With theoretical underpinnings from the fields of cognitive psychology, management, and information systems, the idea of brain overload is defined and explored, from its impact on our decision-making and memory to how we may cope with the resultant 'technostress'. Discussing the negative consequences of technology on work substitution, technologically induced work-family conflicts, and organizational design as well as the initiatives set up to combat these, the authors go on to propose measurement approaches for capturing the entangled aspects of IT-related overload. Concluding on an upbeat note, the book's final chapter explores emerging technologies that can illuminate our world when mindfully managed. Designed to better equip humans for dealing with new technologies, supported by case studies, and also exploring the idea of 'IT addiction', the book concludes by asking how IT processes may aid rather than hinder our cognitive functioning. This is essential reading for anyone interested in how we function in the digital age. © 2019 Anne-Françoise Rutkowski and Carol S. Saunders. All rights reserved.
... The suggestion that amount of cognitive effort affects performance after brain damage has been around since the beginning of research on language and the brain (see review in Monetta & Joanette, 2003). Monetta and Joanette reviewed data from dual-task, divided visual-field studies and studies designed to elicit "disordered" performance from adults without brain damage by increasing the level of difficulty of a task or a response (Monetta, Ouellet-Plamodon, & Joanette, 2006). ...
... They asserted that communication processes frequently reported to be affected after RHD, including interpreting metaphors, discourse-level language, and pragmatics, lie on the complex end of the continuum of language abilities and that the contribution of cognitive resources cannot be ignored as a component of the communication deficits associated with RHD. They indicated that this hypothesis is not designed to replace any other accounts, but rather should be considered along with hypotheses for specific abilities (Monetta & Joanette, 2003). ...
To describe the current treatment research for communication (prosodic, discourse, and pragmatic) deficits associated with right hemisphere brain damage and to provide suggestions for treatment selection given the paucity of evidence specifically for this population.
The discussion covers (a) clinical decision processes and evidence-based practice; (b) a review of right hemisphere communication deficits and existing treatment studies; (c) accounts of right hemisphere function, right hemisphere deficits, and theoretically motivated treatments; and (d) a guide for exploring and selecting treatments based on deficits rather than etiology.
Controlled treatment studies for communication deficits specifically for adults with right hemisphere brain damage are limited to aprosodia. For other communication deficits, clinicians may select treatments based on current theories of right hemisphere function and right hemisphere deficits, and/or treatments developed for other etiologies for which deficits are similar to those associated with right hemisphere damage.
... The suggestion that amount of cognitive effort affects performance after brain damage has been around since the beginning of research on language and the brain (see review in Monetta & Joanette, 2003). Monetta and Joanette reviewed data from dual-task, divided visual-field studies and studies designed to elicit "disordered" performance from adults without brain damage by increasing the level of difficulty of a task or a response (Monetta, Ouellet-Plamodon, & Joanette, 2006). ...
... They asserted that communication processes frequently reported to be affected after RHD, including interpreting metaphors, discourse-level language, and pragmatics, lie on the complex end of the continuum of language abilities and that the contribution of cognitive resources cannot be ignored as a component of the communication deficits associated with RHD. They indicated that this hypothesis is not designed to replace any other accounts, but rather should be considered along with hypotheses for specific abilities (Monetta & Joanette, 2003). ...
... The classic idea of limited cognitive resources has been applied to account for aphasic language deficits (Murray, 1999), but also as an explanation for interhemispheric cross-talk (Weissman & Banich, 2000). Monetta and Joanette (2003) suggested that the right hemisphere comes into play during complex and demanding language tasks (cf. Meyer, Friederici, & von Cramon, 2000;Ferstl & von Cramon, 2001a). ...
... A replication of this study with matched difficulty level of the plausibility judgment task could answer the question of whether the right hemisphere played a role in nonliteral interpretation or whether it was involved merely because of increased task demands (cf. Bookheimer, 2002;Monetta & Joanette, 2003). ...
Higher Level Language Processes in the Brain is a groundbreaking book that explains how behavior research, computational models, and brain imaging results can be unified in the study of human comprehension. The volume illustrates the most comprehensive and newest findings on the topic. Each section of the book nurtures the theoretical and practical integration of behavioral, computational, and brain imaging studies along a different avenue, and each is supplementary. Readers with limited background knowledge on the methods are presented with an easy-to-read, state-of-the-art exposition that is conceptualized and written from a well-established point of view.
Higher Level Language Processes in the Brain is intended for advanced undergraduate and graduate cognitive science students, as well as researchers and practitioners who seek to learn and apply scientific knowledge about human comprehension to reading analysis.
... The majority of reported and recommended treatments for communication deficits associated with RHBD and TBI rely on metalinguistic judgments and understanding decontextualized phrases, such as matching phrases to pictures or defining idioms and metaphors. The added cognitive demands of such tasks have been shown to reduce performance in adults with RHBD (Monetta & Joanette, 2003;Tompkins, Boada, & McGarry, 1992;Tompkins et al., 2002). However, positive results have been reported for metalinguistic and metacognitive treatments for individuals with TBI (e.g., Helffenstein & Wecshler, 1982;Kennedy et al., 2002). ...
... As noted in the introduction, adults with RHBD may exhibit cognitive deficits in conjunction with (or underlying) the communication deficits discussed above (e.g., Martin & McDonald, 2003;McDonald, 2000;Monetta & Joanette, 2003;Monetta, Ouellet-Plamodon, & Joanette, 2006;Tompkins et al., 2013). Much is known about attentional deficits (in particular, visuospatial neglect) and anosognosia (reduced awareness of deficits) in this population. ...
Purpose:
The purpose of this review is to evaluate and summarize the research evidence related to the treatment of individuals with right hemisphere communication disorders.
Method:
A comprehensive search of the literature using key words related to right hemisphere brain damage and communication treatment was conducted in 27 databases (e.g., PubMed, CINAHL). On the basis of a set of pre-established clinical questions, inclusion/exclusion criteria, and search parameters, studies investigating sentence- or discourse-level treatments were identified and evaluated for methodological quality. Data regarding participant, intervention, and outcome variables were reported.
Results:
Only 5 studies were identified, each representing a different sentence- or discourse-level treatment approach and reporting a wide range of prosodic, expressive, receptive, and pragmatic outcomes.
Conclusion:
Although the state of the evidence pertaining to right hemisphere communication treatments is at a very preliminary stage, some positive findings were identified to assist speech-language pathologists who are working with individuals with right hemisphere brain damage. Clinical implications and recommendations for future research are explored.
... Verbal communication can be conceived as the result of a complex left-/righthemisphere (LH/RH) dynamics in which each hemisphere makes both specific and nonspecific cognitive contributions (Monetta & Joanette, 2003;Weissman & Banich, 2000). As appears to be the case for face recognition, memory, object perception, and musical abilities, each hemisphere's involvement must be conceived of in terms of its relative contribution to a complex system of interhemispheric cooperation (Sergent, 1994). ...
... For instance, verbal communication is known to require specific linguistic processes such as those sustaining syntax or phonology, as well as non-specific processes such as working memory and attention (Caplan & Waters, 1999). In this respect, it is possible that LH-based networks contribute more to the implementation of the most specific processes for language, whereas other networks extended over both hemispheres could contribute to non-specific processes such as the amount of available cognitive resources (see Monetta & Joanette, 2003). ...
The goal of this study was to contribute to a better understanding of the relative impacts of age and the occurrence of a right-hemisphere lesion on the processing of the non-literal alternative meanings of words. Eighty healthy individuals participated in this study. Participants were divided into two groups: the older group included participants between 50 and 65 years old whereas the younger group included participants between 20 and 30 years old. Participants performed a semantic pairing task involving metaphorical and non-metaphorical alternative meanings of words and a countdown task. There were two different task presentation conditions: (1) non-interfering context task in which participants completed the main task (word-triad task) without any interference, and (2) interfering-context task in which the word-triad task and the countdown task were executed simultaneously. The main results indicated an age-related change in the processing of the non-literal alternative meanings of words. The most interesting result was that the resource-limiting condition had an impact only on the young adult group.
... The more complex or contrived the task is, the more likely it is that adults with RHD will exhibit impaired performance (e.g. Monetta and Joanette 2003;Tompkins et al. 2012). This is especially apparent when there are metacognitive or metalinguistic demands which require participants to think about their thought processes. ...
Pragmatic deficits are a key component of the communication disorders related to right hemisphere brain damage. The deficits are heterogeneous and include expression and comprehension of prosody, emotion, humor and non-literal language, as well as discourse production and theory of mind. These pragmatic processes are complex and are subserved by extensive neural networks which often include both right and left hemisphere regions. As a result, it is rare to find clear connections between lesion localization and behavior, simple dichotomies of strengths and weaknesses, or consistent patterns of deficits across clients. More research is needed to explore the functional consequences of these deficits and how they can best be treated to improve quality of life for our clients with right hemisphere damage.
... Thus, if impliciture interpretations are driven mostly by linguistic factors, damage to the left hemisphere should result in poor performance on impliciture processing. Additionally, the role of the right hemisphere may be to contribute processing resources (such as attention) to the language abilities of the left hemispheres (Monetta & Joanette, 2003). As such, the cerebral hemispheres may work together for normal impliciture comprehension. ...
... Mental resource limitations (e.g. in attention) may be used to explain deficits in any communicativelyimpaired group, but this explanation may risk being "too seductive" (Tompkins, 1995, p. 80). A cognitive resource limitation such as attention may play a role in accounting for the right hemisphere's verbal communication abilities, but this may be complementary to other explanatory hypotheses (Monetta & Joanette, 2003;Tompkins, 2008). It would seem that a more detailed analysis of the attention deficits exhibited by participants with RBD, related to their performance on a variety of discourse tasks, would provide support for the role played by attention limitations in their communication deficits. ...
This study examined the effects of right brain-damage (RBD) on oral discourse production using a multi-layered discourse processing model. Narrative and procedural discourse samples from participants with RBD and no brain damage were analysed in terms of seven broad areas corresponding to the processing levels of the model. Participants also completed attention, cognitive, general communication and RBD assessments. Despite their normal performance on all assessments (except those on attention), the participants with RBD demonstrated statistically significant differences in syntactic complexity, clarity disruptors and dysfluencies, as well as in discourse grammar and clausal structure in the narratives and in cohesion in the procedures. A model-based theoretical explanation accounting for the deficits noted in participants with RBD, together with clinical guidelines, is provided.
... The identified cognitive-pragmatic profiles can then be taken into account when planning therapy (Blake, 2007;Tompkins, 2012). For example, deficits in the high EF conditions of the IRRI test, associated with deficient EF tests, could reflect insufficient cognitive resources (Cognitive Resources Hypothesis; see Monetta & Joanette, 2003 for a review). Manipulating the complexity of the stimuli used in therapy will, therefore, be of primary importance. ...
Objective
Nonliteral language comprehension disorders in individuals with acquired brain injuries (ABI) are frequently reported in the literature but rarely assessed in clinical settings. A major reason is the lack of tools available to clinicians. Therefore, the present study aimed to further promote the pragmatic assessment routine by creating a new nonliteral language comprehension tool for ABI individuals: the IRRI test. This tool is intended to be standardized and capable of directing clinicians to cognitive deficits underlying a poor understanding of nonliteral language—context processing, executive functions, and theory of mind.
Method
Three studies were conducted. The first study aimed at constructing the two IRRI test tasks: the irony and indirect requests comprehension tasks. These tasks integrate the cognitive processes within them. The second study aimed at analyzing the tasks’ psychometric qualities in a sample of 33 ABI participants and 33 healthy participants (HC). Preliminary normative data obtained from 102 healthy French-speaking subjects were collected in the third study.
Results
Significant differences in the IRRI test’s performances were observed between the ABI and HC individuals. The indirect requests task demonstrated robust convergent validity and good sensibility to discriminate altered participants among ABI participants. Both IRRI test’s tasks also showed excellent test–retest and inter-rater reliability. The preliminary norms were stratified according to the conditions of interest in relation to the cognitive mechanisms underlying the understanding of nonliteral language.
Conclusions
The IRRI test is a promising new standardized test of nonliteral language comprehension, which contributes to identifying cognitive-pragmatic profiles to guide therapy.
... These findings argue that there is an important interaction between verbal WM capacity and the ability to comprehend metaphorical language in PD, and perhaps other pragmatic abilities, which are known to be dependent on intact WM/fronto-striatal systems which deteriorate in PD. More generally, these data fit with theories which state that many language processing deficits produced by brain damage can be explained by the individual resource capacity of individual patients (e.g., Caplan, Waters, DeDe, Michaud, & Reddy, 2007; McNeil, Odell, & Tseng, 1991; Monetta & Joanette, 2003). However, the literature on this topic remains sparse and there are few empirical data that exemplify which socialpragmatic processes of language depend critically on intact WM functions in PD. ...
A group of non-demented adults with Parkinson's disease (PD) were studied to investigate how PD affects pragmatic-language processing, and, specifically, to test the hypothesis that the ability to draw inferences from discourse in PD is critically tied to the underlying working memory (WM) capacity of individual patients [Monetta, L., & Pell, M. D. (2007). Effects of verbal working memory deficits on metaphor comprehension in patients with Parkinson's disease. Brain and Language, 101, 80–89]. Thirteen PD patients and a matched group of 16 healthy control (HC) participants performed the Discourse Comprehension Test [Brookshire, R. H., & Nicholas, L. E. (1993). Discourse comprehension test. Tucson, AZ: Communication Skill Builders], a standardized test which evaluates the ability to generate inferences based on explicit or implied information relating to main ideas or details presented in short stories. Initial analyses revealed that the PD group as a whole was significantly less accurate than the HC group when comprehension questions pertained to implied as opposed to explicit information in the stories, consistent with previous findings [Murray, L. L., & Stout, J. C. (1999). Discourse comprehension in Huntington's and Parkinson's diseases. American Journal of Speech–Language Pathology, 8, 137–148]. However, subsequent analyses showed that only a subgroup of PD patients with WM deficits, and not PD patients with WM capacity within the control group range, were significantly impaired for drawing inferences (especially predictive inferences about implied details in the stories) when compared to the control group. These results build on a growing body of literature, which demonstrates that compromise of frontal–striatal systems and subsequent reductions in processing/WM capacity in PD are a major source of pragmatic-language deficits in many PD patients.
... More recent work from other labs continues to support this view. 11 This account specifies that in domains historically considered problematic for the RHD population, comprehension varies substantially with the attentional or working memory demands of a language task. In addition, these results suggest that the right hemisphere contributes mental resources to perform demanding language tasks. ...
Although the left hemisphere of the brain has long been linked with language, the right cerebral hemisphere also contributes importantly to cognitive operations that underlie language processing and communicative performance. Adults with right hemisphere damage (RHD) typically do not have aphasia, but they often have communication disorders that may have a substantial impact on their social functioning. After a brief summary of communicative and cognitive characteristics of RHD in adults and of extant theoretical accounts of common communicative difficulties, this article discusses rehabilitation issues, approaches, evidence, and needs.
... Resources are an individually possessed form of physical, emotional or cognitive energy required in processing information [8,9]. Resources are limited; thus, they form a pool and affect each other through a feedback loop [10,11]. The complexity of technologies in the OR requires surgeons to allocate their resources mindfully to reach optimal surgical results [3]. ...
Background
Minimally invasive surgery requires surgeons to allocate more attention and efforts than open surgery. A surgeon’s pool of resource is affected by the multiple occurrences of interruptions and distractions in the operating room. Surgical flow disruption has been addressed from a quantitative perspective. However, little is known on its impact on the surgeons’ physiological resources.
Methods
Three physiological markers, heat flux (HF), energy expenditure in metabolic equivalent of tasks and galvanic skin response were recorded using body sensor monitoring during the 21 surgical operations. The three markers, respectively, represent: stress, energy mobilization and task engagement. A total of 8 surgeons with different levels of expertise (expert vs. novice) were observed performing 21 surgical procedures categorized as short versus long. Factors of distractions were time-stamped, and triangulated with physiological markers. Two cases illustrate the impact of surgical flow disruptions on the surgeons.
Results
The results indicate that expert surgeons’ mental schemata are better organized than novices. Additionally, the physiological markers indicate that novice surgeons display a higher HF at the start (tendency p = .059) and at the end of procedures (p = .001) when compared to experts. However, during longer procedures, expert surgeons have higher HF at the start (p = .041) and at the end (p = .026), than at the start and end of a short procedure.
Conclusion
Data collected during this pilot study showed that interruptions and disruptions affect novice and expert surgeons differently. Surgical flow disruption appears to be taxing on the surgeons’ mental, emotional and physiological resources; as a function of the length and nature of the disruptions. Several training curricula have incorporated the use of virtual reality programs to train surgeons to cope with the new technology and equipment. We recommend integrating interruptions and distractions in virtual reality training programs as these impact the surgeons’ pool of resources.
... Moreover, a growing body of studies suggests that the increased RH involvement in processing metaphorical language is more likely a reflection of language complexity than of language specialization (Lee & Dapretto, 2006). In accordance with that hypothesis, some authors have actually proposed that RH involvement is necessary whenever language processing becomes complex (Monetta & Joanette, 2003;Monetta et al., 2006). But if that is correct, the phonological results should be similar to the semantic ones, since two levels of complexity were evaluated in both cases. ...
The main goal of this study was to determine whether the phonological and semantic processing of words are similarly influenced by an increase in processing complexity. Thirty-six French-speaking young adults performed both semantic and phonological word judgment tasks, using a divided visual field procedure. The phonological complexity of words was controlled by varying their transparency, while semantic complexity was manipulated through prototypicality. As expected, processing complexity modulated semantic and phonological processing differently. The results revealed that an increase in processing complexity lessened the left-hemisphere advantage in semantics, but reinforced it in phonology. It is therefore suggested that right-hemisphere collaboration in complex language processing is profitable only when the particular kind of processing is not strongly lateralized to the left-hemisphere. The results are discussed from the perspective of interhemispheric collaboration.
... This increased difficulty controlling interference consumes processing resources, which are then unavailable for other levels of language processing (Green, 1998), resulting in reduced accessibility of that language. Similarly, cognitive-resource deficits appear to play a substantial role in aphasia (see, Monetta & Joanette, 2003). In particular, inhibition mechanisms including interference control are often impaired in aphasia, resulting in a slowing of language processing (Szöllősi & Marton, 2016). ...
Language difficulties can arise from reduced exposure to any given language (e.g. attrition) or after brain damage (e.g. aphasia). The manifestations of attrition and aphasia are often similar so differentiating between their effects on language loss and recovery is challenging. We investigated treatment effects for an English-Hebrew bilingual person with stroke-induced aphasia who had minimal contact with his Hebrew for over 14 years. We asked whether his attrited language could be rehabilitated, how effects of attrition and aphasia can be dissociated, and how such dissociation aids our understanding of the mechanisms involved in language recovery in aphasia. We administered a verb-based semantic treatment in Hebrew three times a week for six weeks (totalling 29 hours of therapy) and assessed changes in both Hebrew and English comprehension and production abilities across a variety of language tasks. Quantitative analyses demonstrated improvement in Hebrew production across language tasks, including those involving lexical retrieval processes that were trained during treatment. Improvement to English occurred in these same lexical retrieval tasks only. We interpret these results as indicating that the participant's attrited language (Hebrew) could be rehabilitated with both specific treatment and general exposure to Hebrew contributing to improvement. Furthermore, treatment effects transferred to the untreated English. Qualitative analyses indicated that an interaction among aphasia, incomplete mastery of Hebrew pre-stroke, and attrition contributed to the participant's language difficulties post-stroke. We conclude that partially shared underlying mechanisms of attrition and aphasia drive language processing and changes to it with treatment.
Pragmatic disruption is associated with a range of acquired communication disorders of both neurogenic and psychiatric origin. This chapter provides an overview of the main themes in the research into pragmatic disruption in people with aphasia, right hemisphere language disorder, schizophrenia, traumatic brain injury, Alzheimer’s dementia, non-Alzheimer dementia and Parkinson’s disease. These disorders are associated with particular patterns of pragmatic disruption which, in some cases, have been linked to disturbances in cognitive abilities, most often in theory of mind and executive function. Pragmatic strengths have typically been overshadowed by a focus on the pragmatic deficits in any given population. However, it is argued that these strengths form a crucial component of the pragmatic presentation of any client or clinical group more generally. Pragmatic disorders have a pervasive impact on the individual with the disorder as well as on those around them. Assessment and intervention in pragmatic disorders of adulthood must account for the profile of deficits and strengths, while considering the broader impact of the disorder on the individual and their social network.
Following reports in the 1960s that language may be affected by right-hemisphere (RH) lesions, many limitations to effective communication in the population with right-hemisphere damage (RHD) have been described. However, stereotypical portrayals and descriptions of carefully selected cases may be misleading as to the extent of communication deficits. In many of the parameters in which RHD patients are presented as typically impaired (e.g. discourse skills), a less severe picture may emerge when data from the non-brain-damaged (NBD) population are considered, controlling for age and education-level variables. Subsequent to RHD, some people show deficits on some communication measures, but many of these communication behaviours are also present in some NBD adults. Thus, diagnosis of deficit must be made with reference both to the healthy peer population and the individual's pre-lesion behaviour. The authors’ RH-stroke research programme includes studies of incidence of communication deficit, comparisons of RHD and NBD groups in various spoken discourse and comprehension tasks, comparison of RHD groups of different ages, detailed analysis of topic within discourse in RHD and NBD groups, family members’ views of communication behaviour following RHD, and the natural course of communication change in the first year after RH stroke. The findings from several studies are summarised and used as the basis for management recommendations, which may guide future outcome research. There is an urgent need for the evaluation of communication management programmes, to determine whether therapists may, with confidence, offer an effective intervention service to those people whose communication skills are affected by RHD.
Résumé
La rééducation des troubles de la communication verbale chez les cérébrolésés droits est
encore peu développée en orthophonie. Une enquête menée en milieux de réadaptation au
Québec sert de base à cet article pour esquisser un cadre général d’intervention. Cela comprend
la prise de décision d’une intervention orthophonique, la définition des objectifs de
traitement, le choix des stratégies de rééducation et l’évaluation de l’efficacité de l’intervention.
Les troubles de la communication des cérébrolésés droits peuvent engendrer des
situations de handicap communicationnel et l’intervention ciblée de spécialistes du langage
et de la communication est primordiale auprès de cette population.
Mots clés : cérébrolésés droits, troubles de la communication, stratégie de rééducation,
efficacité de l’intervention, MEC, counseling.
Speech and language therapy in right-hemisphere damaged patients
Abstract
The rehabilitation of communication disorders in right-hemisphere damaged individuals is
not yet greatly developed in speech and language pathology. In the present article, a survey
conducted in rehabilitation centres in Quebec provides the basis for drawing the outline of a
general intervention framework, including the decision to initiate therapy, the definition of
treatment goals, the choice of intervention strategies and the evaluation of treatment efficacy.
Right-hemisphere damaged individuals with communication disorders might experience
situations of communicational handicap and it is essential that speech and language
pathologists use targeted interventions with this population.
Key Words : right-hemisphere damaged individuals, communication disorders, rehabilitation
strategies, intervention efficacy, MEC, counseling.
Kimelman and McNeil (1987) suggested that improved auditory comprehension for emphatically stressed information might be attributed to recruitment of additional processing resources. This study investigated effects of emphatic stress when it was applied to target words during a semantic judgement task on the auditory processing of non-stressed targets for a lexical decision task. Response time and accuracy were analysed for this dual-task experiment. It was first established that the stimuli contained appropriately placed stressed lexical items and that all subjects benefited from the emphatic stress. Next it was established that all subjects were able to voluntarily trade processing resources in the dual task under investigation, and were able to generate a performance operating curve (POC). Normal subjects showed the predicted performance decrement on the non-stressed word in the context of the preceding stressed word; subjects with aphasia did not. Results are discussed relative to resource allocation theory with normal subjects, and a working memory explanation for aphasic subjects' performance.
Tested a multiple resources approach to time-sharing performance which assumes that each cerebral hemisphere controls its own set of processing resources that it cannot share with the other hemisphere. Right-handed men performed a verbal memory task while concurrently tapping the index finger of either hand as rapidly as possible. Task priority was manipulated with a payoff scheme. Ss remembered more on the verbal task when concurrently tapping with their left hands than when tapping with their right hands, and their memory performance was much better when the memory task was emphasized than when the tapping task was emphasized, regardless of hand. For the tapping task, decrements from baseline tapping rates and trade-offs between tasks were equal for both hands when Ss were reading the to-be-remembered words aloud. In contrast, during the retention interval, decrements were larger for the right hand than the left, and there were no task trade-offs. On right-hand trials, both tasks required exclusively left-hemisphere resources, whereas on left-hand trials, right-hemisphere resources were required to execute the tapping movements per se, but left-hemisphere resources were necessary to coordinate those movements with the movements required for overt speech. The data underscore the importance of manipulating task priority to obtain an accurate picture of a task's resource requirements. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
The literature on practice effects and transfer from single- to dual-task performance is briefly reviewed. The review suggests that single-task training produces limited transfer to dual-task performance. Past theoretical frameworks to explain multitask performance are reviewed. A connectionist/control architecture for skill acquisition is presented. The architecture involves neural-like units at the micro level of processing, with information transmitted between modules at the macro level. Simulations within the architecture exhibit five phases of skill acquisition. Dual-task interference and performance are predicted as a function of the phase of practice a skill has reached. Seven compensatory activities occur in the architecture during dual-task training that do not appear in single-task training, including (1) shedding and delaying tasks and preloading buffers, (2) letting go of high-workload strategies, (3) utilizing noncompeting resources, (4) multiplexing over time, (5) shortening transmissions. (6) converting interference from concurrent transmissions, and (7) chunking of transmissions. Future research issues suggested by the architecture are discussed.
Two experiments tested the limiting case of a multiple resources approach to resource allocation in information processing. In this framework, the left and right hemispheres are assumed to have separate, limited-capacity pools of undifferentiated resources that are not mutually accessible, so that tasks can overlap in their demand for these resources either completely, partially, or not at all. We tested all three degrees of overlap in demand for left hemisphere supplies, using dual-task methodology in which subjects were induced to pay different amounts of attention to each task. Experiment 1 compared complete and partial overlap by combining a verbal memory load with a task in which subjects named nonsense syllables briefly presented to either the left or right visual field (LVF and RVF, respectively). Experiment 2 compared complete versus no overlap by using the same verbal memory load combined with a laterally presented same-different judgment task that did not require a spoken response. Decrements from single-task performance were always more severe when the visual field task stimulus was presented to the RVF. Further, subjects in Experiment 1 were able to trade performance between tasks on both LVF and RVF trials because there was always at least some overlap in left hemisphere demand. In Experiment 2, performance trade-offs were observed on RVF (complete overlap) trials, but not on LVF trials, where no overlap in demand existed. These results contradict a single-capacity model, but they support the idea that the hemispheres' resource supplies are independent and have implications for both cerebral specialization and divided attention issues.
Because interaction of the cerebral hemispheres has been found to aid task performance under demanding conditions, the present study examined how this effect is moderated by computational complexity, the degree of lateralization for a task, and individual differences in asymmetric hemispheric activation (AHA). Computational complexity was manipulated across tasks either by increasing the number of inputs to be processed or by increasing the number of steps to a decision. Comparison of within- and across-hemisphere trials indicated that the size of the between-hemisphere advantage increased as a function of task complexity, except for a highly lateralized rhyme decision task that can only be performed by the left hemisphere. Measures of individual differences in AHA revealed that when task demands and an individual's AHA both load on the same hemisphere, the ability to divide the processing between the hemispheres is limited. Thus, interhemispheric division of processing improves performance at higher levels of computational complexity only when the required operations can be divided between the hemispheres.
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.
Research and clinical efforts aimed at understanding and improving the communication impairments associated with acquired right hemisphere damage (RHD) are hampered by lack of a formal definition or label. This paper addresses that issue in light of the recent proposal by Joanette and Anslado (1999a, b) that RHD communication disorders be called "Pragmatic Aphasia". Underlying assumptions regarding the use of the term aphasia to describe these deficits and the concept that pragmatics is inherent to language are questioned. The potential value of "pragmatics" as it relates to communicative intents, and its potential application to a definition of RHD communication impairments are also explored.
Our recent article (Miyake, Carpenter,&Just, 1994) posits that comprehension breakdown in aphasic patients arises, in part, from reduced working memory resources for language. One issue that we consider in this article concerns the nature of the deficits postulated in the theory, in contrast to two alternative views of the deficit: (1) a proposal cast in terms of a partial loss of knowledge rather than reduced resources, and (2) a proposal that there is a separate resource pool for syntactic processing, rather than a more general pool for language comprehension. A second issue that we address here concerns patterns of selective sparing and impairment among some patients that have often been interpreted as indicating specific impairments in sentence processing operations. We argue that such micro-level dissociations at a fine-grain level of analysis can arise for many reasons other than selective impairments and, more specifically, that the occurrence of analogous patterns in normal adults challenges the common interpretations of double dissociations regarding sentence comprehension deficits.
Background: Comprehension deficits that typify adults with right brain damage (RBD) have been linked to considerations of processing capacity and processing demands, as well as to ineffective suppression of mental activation that is incompatible with a contextually intended interpretation. Aims: As a first step in investigating how processing resource factors and more specific difficulties like suppression deficits interact to yield characteristic RBD comprehension patterns, the current study was designed to assess whether suppression function consumes attention. Methods & Procedures: A total of 28 RBD and 22 non-brain-damaged adults listened to sentence stimuli that biased the meaning of a sentence-final lexical ambiguity (e.g., “spade”). The suppression task involved speeded judgements of whether a subsequent spoken probe word fitted the overall sentence meaning. In experimental stimuli, the probe word (e.g., “cards”) was unrelated to the biased meaning of the ambiguity. Comparison stimuli ended in an unambiguous word (e.g., “shovel”) that was clearly unrelated to the spoken probe. Thus, slowness after an experimental sentence, relative to its comparison sentence, indicated that the contextually inappropriate meaning of the experimental ambiguity interfered with the probesentence relatedness judgement (i.e., had not been suppressed). In two dual-task conditions, participants allocated 20% or 50% of their “brain power” to a concurrent secondary task, reporting orally whether the probe word consisted of one or two syllables. Outcomes & Results: For both groups, suppression of contextually unintended meanings of lexical ambiguities was more effective in a single-task condition than when attention was shared with a secondary task. The secondary syllable-counting task also suffered when allocated less attention. Conclusions: Effective suppression consumes finite processing capacity. As elaborated in the paper, several combinations of these variables could underlie relatively good and poor comprehension after RBD. Researchers and clinicians need to keep in mind such potential interactions of ineffective comprehension mechanisms, stimulus/task processing demands, and processing capacity.
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)
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.
Problems associated with scaling and normalizing empirical performance operating characteristics (POCs) are examined. Normalization methods proposed by Wickens (1980) and by Mountford and North (1980) are critically evaluated. Computer simulations are used to generate raw-score and normalized POCs. The interpretation of transformed empirical POCs (Wickens, Mountford, and Schreiner, 1981) is shown to contain inconsistencies. The normalization techniques reviewed fail to resolve POC scaling problems. Caution must be exercised when interpreting transformed POCs.
Appreciation of metaphoric and nonmetaphoric alternative word meanings was assessed in 19 aphasic, left (LHD) and 15 non-aphasic, right (RHD) hemisphere brain-damaged stroke patients. With the one exception in the aphasic group, all patients were male. In an unspeeded sorting task, subjects responded on the basis of less frequent, alternative meanings of polysemous target words. Targets were either polysemous adjectives (e.g. "warm") having metaphoric alternative meanings (loving) or polysemous nouns (e.g., "pen") having non-metaphoric alternative meanings (writing implement, cage). Both patient groups performed worse overall than a group of nonbrain-damaged control subjects. Relative to the RHD patients, LHD patients showed a spared appreciation of metaphoric alternative meanings. In addition, LHD, but not RHD, patients performed better on metaphoric adjective trials when there was high similarity between a word's dominant and (metaphoric) alternative meaning. The results suggest a pervasive insensitivity of RHD patients to alternative interpretations of linguistic units, and a special role for the intact right hemisphere in lexical-semantic processes related to metaphor comprehension.
Signal detection measures were used to evaluate the effects of several response variables (manual vs. vocal, Go-NoGo vs. Yes-No) on lexical decision asymmetries. An unvarying right visual field advantage in discriminability (d') was observed in each condition. However, response criteria (beta) varied over visual fields and conditions. Naming and lexical decision were shown to have equivalent asymmetries when the effects of response bias are removed. The results indicate that postaccess decision processes make important contributions to lexical decision asymmetries.
Nine aphasic and 18 normal adults participated in a dual task with components of phoneme monitoring and semantic judgment. Subjects listened to lists of recorded spoken words and were required to detect semantic and phonetic targets. Two within-subject variables were manipulated: the probability of target occurrence for each dual-task component (.2, .5, and .8) and the explicitness of instruction (explicit vs. implicit). Only in the explicit condition were subjects told about the probability structure and given the attention allocation strategy congruent with that structure. Reaction times were recorded on-line for analysis by an IBM-AT. The results showed that normal subjects' overall latencies in detecting phonetic targets decreased as the target occurrence probability increased in both implicit and explicit instruction conditions. The detection latencies for semantic targets showed a similar probability effect but only in the explicit condition. By contrast, the aphasic subjects did not show the probability effect in any condition, although they performed above the chance level on both semantic and phonetic tasks. The presence of the probability effects for the normal subjects indicated that an efficient attention allocation mechanism was operating so as to optimize the performance level. On the other hand, the absence of probability effects for the aphasic subjects suggests that their attention control system might be inefficient so that task-demand cues (probability and attention allocation instruction) were not utilized properly.
After listening to multiple-episode stories that promoted coherence inferences, right hemisphere-damaged patients answered Inference questions about the stories less accurately than Explicit questions, whereas normal elderly subjects answered both question types equally well. In addition, while subjects listened to the stories they made lexical decisions to tests words that were related to the promoted inferences or were unrelated to the stories. Right hemisphere-damaged patients responded more slowly to inference-related words than to unrelated words, whereas normal elderly subjects responded more quickly to interference-related words than to unrelated words. Furthermore, the episode boundaries did not affect either group's accuracy on Inference questions, and the boundaries equally affected both groups' lexical decision latencies, suggesting that the patients' inferencing deficit was not due to an impairment in organizing the mental substructures used to represent discourse. These results suggest that the right hemisphere-damaged patients lacked activation of semantic information necessary for drawing coherence inferences.
The proposition that visual field asymmetries can be produced through priming the left hemisphere with verbal material was investigated. In the first experiment a two-choice neutral detection task was established to measure biases of attention between the visual fields. In the second experiment, a priming effect was achieved by superimposing each trial with a verbal recognition task. Reaction time and error measures showed no sign of a right visual field advantage. In the third experiment, the neutral detection trials were intermixed with trials associated with a word recognition task. A significant right visual field advantage was found for the word recognition task. However, this pattern of asymmetry was not found for the neutral detection task. In the fourth experiment the level of difficulty associated with neutral detection task was increased. The effect of expectancy was investigated by manipulating the proportion of neutral and verbal stimuli. Despite these manipulations, the pattern of results was essentially the same as those observed in the previous experiment. These experiments demonstrate that verbal priming does not affect the distribution of spatial attention.
ERPs were recorded while subjects were reading short familiar metaphors (e.g., Those fighters are lions), unfamiliar metaphors (Those apprentices are lions), or literal control sentences (Those animals are lions) presented in isolation or preceded by either an irrelevant or relevant context (e.g., They are not idiotic: ...." vs. "They are not cowardly: Those fighters are lions"). The terminal word of metaphors elicited larger N400 components than did the terminal word of literal sentences (Experiment 1) suggesting that the (incongruous) literal meaning of metaphors was indeed accessed at some point during comprehension. The analysis of the 600-1000 and 1000-1400 latency bands (Late Positive Components) revealed no significant difference between metaphors and literal sentences. The manipulation of metaphor difficulty (Experiments 2 and 3) also failed to reveal any late effect specifically linked to metaphorical processing. Finally, an effect of the preceding sentence context was found in Experiments 3 and 4, as early as 300 ms following the terminal word onset. Overall, these results support a context-dependent account of metaphor comprehension stating that when contextually relevant, the metaphorical meaning is the only one accessed.
This article describes a new computational model of aphasic sentence comprehension. The model is based on the premise that all aphasics, however different, share a common deficit which determines a considerable amount of the individual variation observed in their sentence comprehension performance. This common deficit is construed as a pathological reduction in the activation resources of a working memory system that subserves sentence comprehension (Miyake, Carpenter, & Just, 1994). To test the theoretical feasibility of the resource reduction hypothesis, a new computer model of aphasic sentence comprehension was developed and tested. We describe the model as well as some initial simulation results, indicating that the model can account for some of the sentence complexity and severity effects that have been reported in the aphasia literature.
Three experiments examined interference effects in concurrent temporal and nontemporal tasks. The timing task in each experiment required subjects to generate a series of 2- or 5-sec temporal productions. The nontemporal tasks were pursuit rotor tracking (Experiment 1), visual search (Experiment 2), and mental arithmetic (Experiment 3). Each nontemporal task had two levels of difficulty. All tasks were performed under both single- and dual-task conditions. A simple attentional allocation model predicts bidirectional interference between concurrent tasks. The main results showed the classic interference effect in timing. That is, the concurrent nontemporal tasks caused temporal productions to become longer (longer productions represent a shortening of perceived time) and/or more variable than did timing-only conditions. In general, the difficult version of each nontemporal task disrupted timing more than the easier version. The timing data also exhibited a serial lengthening effect, in which temporal productions became longer across trials. Nontemporal task performance showed a mixed pattern. Tracking and visual search were essentially unaffected by the addition of a timing task, whereas mental arithmetic was disrupted by concurrent timing. These results call for a modification of the attentional allocation model to incorporate the idea of specialized processing resources. Two major theoretical frameworks--multiple resource theory and the working memory model--are critically evaluated with respect to the resource demands of timing and temporal/nontemporal dual-task performance.
Recent advances in the field of communication sciences have led to the description of acquired communication disorders affecting pragmatic skills in patients with brain damage. The present article discusses the impact of such findings on the clinical concept of aphasia. Through reference to a number of articles contained in this Special Issue, it must be reiterated that pragmatic and other linguistic components of communication abilites are two sides of a same coin-that of language-and intimately interrelated. It is also argued that the difference between traditional (e.g., syntax) and pragmatic components of language cannot be explained in simple terms such as the former being subserved only by linguistic processes and the latter by other cognitive processes. Pragmatic components are thus to be considered as part of language. The evolution of the concept of language has a direct impact on the clinical concept of aphasia. Indeed, if aphasia corresponds to an acquired impairment of language, then pragmatic impairments must be considered part of aphasia. The inclusion of pragmatic impairments in the concept of aphasia does not hold only when they occur within the frame of classic types of aphasia, but also when they occur in isolation. Consequently, a new type of aphasia-pragmatic aphasia-should be considered and defined in order to describe the clinical condition of those individuals suffering from acquired pragmatic disorders as those reported among right-hemisphere-damaged right-handers. It is concluded that the recent evolution around the concept of language should be followed by an evolution of the concept of aphasia per se.
Three experiments were designed to examine whether task complexity determines the degree to which a division of processing across the hemispheres (i.e., across-hemisphere processing) underlies performance when within- and across-hemisphere processing are equally possible. When task complexity was relatively low, performance in a midline condition that allowed for either within- or across-hemispheric processing resembled within-hemisphere performance (Experiments 1 and 2). However, when task complexity was high, performance in a midline condition (Experiments 1 and 2) and a lateralized condition, which also allowed for either within- or across-hemisphere processing (Experiment 3), resembled across-hemisphere performance. Results complement and extend prior work (e.g., M. T. Banich & A. Belger, 1990) by indicating that the degree to which interhemispheric cooperation underlies performance changes with the complexity of the task being performed. This finding suggests that the hemispheres dynamically couple or uncouple their processing as a function of task complexity.
Adults with mild aphasia, right hemisphere brain damage (RBD), or no brain damage (NBD) provided one-word phrase completions under isolation, focused attention, and divided attention conditions and in response to relatively constrained or unconstrained phrase stems. Despite comparable word retrieval accuracy among groups during the isolation condition, aphasic and RBD groups performed less accurately than the NBD group during focused and divided attention conditions. Across conditions, there were no significant differences between aphasic and RBD groups. Only aphasic subjects demonstrated a significant effect of phrase type, responding more accurately when completing constrained versus unconstrained stimuli. For aphasic and RBD groups, error type analysis indicated that semantic and phonological aspects of word retrieval were influenced by increased attentional demands. These findings suggest that for adults with aphasia or RBD, there is a negative relation between attention impairments and word retrieval abilities.
Recordings of neuronal activity in humans have identified few correlates of the known hemispheric asymmetries of functional lateralization. Here, we examine single-unit activity recorded from both hemispheres during two delayed match-to-sample tasks that show strong hemispheric lateralization based on lesion effects; a line-matching (LM) task related to the right hemisphere, and a rhyming (RHY) task related to the left. Nineteen neuronal populations were recorded with extracellular microelectrodes from the left temporal neocortex of 11 awake patients, and 18 from the right in 9 patients during anterior temporal lobectomy for complex partial seizures under local anesthesia. All subjects were left hemisphere dominant for language. Twelve (32%) populations exhibited statistically significant changes in activity at p <.05. Although changes in firing frequency were recorded from both hemispheres during both tasks, the RHY task elicited changes in activity several hundred milliseconds earlier on the left side than on the right. The LM task, on the other hand, induced changes earlier on the right side than on the left. Both hemispheres contained units active during verbal responses regardless of which behavior elicited the response. Our results indicate that cerebral dominance is reflected in earlier neuronal activity in the anterior temporal lobe during tasks lateralized to that hemisphere.
Using visual half-field presentations of words to the right (RVF) and to the left visual field (LVF), this study investigated the time course of the hemispheric involvement in the processing of semantic category information. Multi-channel event related brain potentials (ERPs) were recorded from 15 healthy subjects during a categorisation task of sequentially presented word pairs. Subjects had to judge mentally after the appearance of the second word whether the words of a pair were semantically related (SR) or not (SU). ERPs were computed, from 100 ms before the onset of the second word to 600 ms, for SR and SU conditions in the LVF and in the RVF separately. The temporal segmentation of ERP map series into sequences of quasi-stable map configurations revealed a total of seven segments in each visual field of which only the first five (S1-S5, appearing between 70 and 400 ms) showed different map configurations as a function of visual field but presented a similar temporal sequence in both visual fields. By contrast, of the last two segments (S6 and S7) which appeared between approximately 400 and approximately 600 ms, only S7 differentiated SR and SU conditions in terms of its duration. Source localisation analysis of the segments showed that following the initial activation of posterior brain regions as a function of the visual field of presentation, a common neural network was activated in the left hemisphere (LH) although the dynamics of activation varied as a function of visual field. Concerning the role of the right hemisphere (RH) in lexico-semantic processing, the results presented here appear to be compatible with a 'callosal relay model' and suggest that, in healthy subjects, information is transferred rapidly ( approximately 150 ms) from the RH to the language dominant-LH.