Non-verbal communication in severe aphasia: Influence of aphasia, apraxia, or semantic processing?

Recovery of gestures for persons with severe non-fluent aphasia and limb apraxia: A long-term follow-up study

Persons with severe non-fluent aphasia would benefit from using gestures to substitute for their absent powers of speech. The use of gestures, however, is challenging for persons with aphasia and concomitant limb apraxia. Research on the long-term recovery of gestures is scant, and it is unclear whether gesture performance can show recovery over time. This study evaluated the recovery of emblems and tool use pantomimes of persons with severe non-fluent aphasia and limb apraxia after a left hemisphere stroke. The Florida Apraxia Screening Test-Revised (FAST-R) was used for measurements. The test includes 30 gestures to be performed (i) after an oral request, (ii) with the aid of a pictorial cue, or (iii) as an imitation. The gestures were rated on their degree of comprehensibility. The comprehensibility of gestures after an oral request improved significantly in five out of seven participants between the first (1-3 months after the stroke) and the last (3 years after) examination. Improvement continued for all five in the period between six months and three years. The imitation model did improve the comprehensibility of gestures for all participants, whereas the pictorial cue did so just slightly. The skill of producing gestures can improve even in the late phase post-stroke. Because of this potential, we suggest that gesture training should be systematically included in the rehabilitation of communication for persons with severe non-fluent aphasia.

The Neurocognitive Bases of Meaningful Intransitive Gestures: A Systematic Review and Meta-analysis of Neuropsychological Studies

Researchers and clinicians have long used meaningful intransitive (i.e., not tool-related; MFI) gestures to assess apraxia-a complex and frequent motor-cognitive disorder. Nevertheless, the neurocognitive bases of these gestures remain incompletely understood. Models of apraxia have assumed that meaningful intransitive gestures depend on either long-term memory (i.e., semantic memory and action lexicons) stored in the left hemisphere, or social cognition and the right hemisphere. This meta-analysis of 42 studies reports the performance of 2659 patients with either left or right hemisphere damage in tests of meaningful intransitive gestures, as compared to other gestures (i.e., MFT or meaningful transitive and MLI or meaningless intransitive) and cognitive tests. The key findings are as follows: (1) deficits of meaningful intransitive gestures are more frequent and severe after left than right hemisphere lesions, but they have been reported in both groups; (2) we found a transitivity effect in patients with lesions of the left hemisphere (i.e., meaningful transitive gestures more difficult than meaningful intransitive gestures) but a "reverse" transitivity effect in patients with lesions of the right hemisphere (i.e., meaningful transitive gestures easier than meaningful intransitive gestures); (3) there is a strong association between meaningful intransitive and transitive (but not meaningless) gestures; (4) isolated deficits of meaningful intransitive gestures are more frequent in cases with right than left hemisphere lesions; (5) these deficits may occur in the absence of language and semantic memory impairments; (6) meaningful intransitive gesture performance seems to vary according to the emotional content of gestures (i.e., body-centered gestures and emotional valence-intensity). These findings are partially consistent with the social cognition hypothesis. Methodological recommendations are given for future studies.

Temporal Overlap Between Gestures and Speech in Poststroke Aphasia: Is There a Compensatory Effect?

PURPOSE

If language production is impaired, will gestures compensate? Evidence in favor of this prediction has often been argued to come from aphasia, but it remains contested. Here, we tested whether thought content not present in speech due to language impairment is manifested in gestures, in 20 people with dysfluent (Broca's) aphasia, 20 people with fluent (Wernicke's) aphasia, and 20 matched neurotypical controls.

METHOD

A new annotation scheme was created distinguishing types of gestures and whether they co-occurred with fluent or dysfluent/absent speech and were temporally aligned in content with coproduced speech.

RESULTS

Across both aphasia types, noncontent (beat) gestures, which by their nature cannot compensate for lost speech content, constituted the greatest proportion of all types of gestures produced. Content (i.e., descriptive, referential, and metaphorical) gestures were largely coproduced with fluent rather than dysfluent speech and tended to be aligned with the content conveyed in speech. They also did not differ in quantity depending on whether the dysfluencies were eventually resolved or not. Neither aphasia severity nor comprehension ability had an impact on the total amount of content gesture produced in people with aphasia, which was instead positively correlated with speech fluency.

CONCLUSIONS

Together, these results suggest that gestures are unlikely to have a role in compensating for linguistic deficits and to serve as a representational system conveying thought content independent of language. Surprisingly, aphasia rather is a model of how gesture and language are inherently integrated and aligned: Even when language is impaired, it remains the essential provider of content.

Unaided communication behaviours displayed by adults with severe cerebrovascular accidents and little or no functional speech: A scoping review

BACKGROUND

Unaided communication behaviours may provide communication support for persons with severe cerebrovascular accidents (CVA), as these individuals often experience severe communication difficulties, regardless of the aetiology. Though often subtle, these behaviours are present during all stages of recovery, and therefore communication partners need to know not only which unaided strategies are used as communication attempts, but also what their function is (i.e., what the person aims to achieve with the communication).

AIM

To identify the unaided communication behaviours that adults with severe CVA and little or no functional speech use to communicate, and to determine the communication functions addressed by these behaviours.

METHODS & PROCEDURES

The study used a scoping review methodology and included articles on communication partners of persons with CVA published between 1986 and 2020. Initially the searches yielded 732 studies from which 211 duplicates were identified. The remaining studies (n = 531) were then screened on title, abstract and full-text level resulting in a final inclusion of 18 studies. Of the 18 studies, five were qualitative and 13 consisted of quantitative methodologies.

MAIN CONTRIBUTION

The subtle communication behaviours used by persons with CVA (and resultant severe communication difficulties) are often misinterpreted or overlooked by their partners. If partners are trained to recognise such subtle or unaided communication behaviours, they can provide adequate support to access a range of communication functions. The unaided communication behaviours, which include 13 primary behaviours ranging from non-linguistic to linguistic, were utilised to convey 31 communication functions classified into four main communication categories.

CONCLUSIONS & IMPLICATIONS

Although unaided communication behaviours often appear as limiting, they can be utilised to communicate various communication functions. The findings of this review support the training of partners to identify these behaviours and improve person-partner communication. WHAT IS KNOWN?: Unaided communication has been widely researched. However, a summary is needed of the various unaided communication behaviours and of the different communication functions addressed by these behaviours. What the paper adds… This paper emphasises that unaided communication behaviours range from non-linguistic to linguistic, and they can support unintentional, pre-intentional and intentional communication functions. Clinical implications Even though aided communication is preferred, unaided communication behaviours are generally used in contexts with limited resources, as well as among culturally and linguistically diverse populations. This study advocates the identification of unaided communication behaviours by partners as well as the support and provision of access to communication strategies for persons with severe CVA. Future research should include more untrained communication partners.

What is Functional Communication? A Theoretical Framework for Real-World Communication Applied to Aphasia Rehabilitation

Aphasia is an impairment of language caused by acquired brain damage such as stroke or traumatic brain injury, that affects a person’s ability to communicate effectively. The aim of rehabilitation in aphasia is to improve everyday communication, improving an individual’s ability to function in their day-to-day life. For that reason, a thorough understanding of naturalistic communication and its underlying mechanisms is imperative. The field of aphasiology currently lacks an agreed, comprehensive, theoretically founded definition of communication. Instead, multiple disparate interpretations of functional communication are used. We argue that this makes it nearly impossible to validly and reliably assess a person’s communicative performance, to target this behaviour through therapy, and to measure improvements post-therapy. In this article we propose a structured, theoretical approach to defining the concept of functional communication. We argue for a view of communication as “situated language use”, borrowed from empirical psycholinguistic studies with non-brain damaged adults. This framework defines language use as: (1) interactive, (2) multimodal, and (3) contextual. Existing research on each component of the framework from non-brain damaged adults and people with aphasia is reviewed. The consequences of adopting this approach to assessment and therapy for aphasia rehabilitation are discussed. The aim of this article is to encourage a more systematic, comprehensive approach to the study and treatment of situated language use in aphasia.

Pantomime of tool use: looking beyond apraxia

Pantomime has a long tradition in clinical neuropsychology of apraxia. It has been much more used by researchers and clinicians to assess tool-use disorders than real tool use. Nevertheless, it remains incompletely understood and has given rise to controversies, such as the involvement of the left inferior parietal lobe or the nature of the underlying cognitive processes. The present article offers a comprehensive framework, with the aim of specifying the neural and cognitive bases of pantomime. To do so, we conducted a series of meta-analyses of brain-lesion, neuroimaging and behavioural studies about pantomime and other related tasks (i.e. real tool use, imitation of meaningless postures and semantic knowledge). The first key finding is that the area PF (Area PF complex) within the left inferior parietal lobe is crucially involved in both pantomime and real tool use as well as in the kinematics component of pantomime. The second key finding is the absence of a well-defined neural substrate for the posture component of pantomime (both grip errors and body-part-as-tool responses). The third key finding is the role played by the intraparietal sulcus in both pantomime and imitation of meaningless postures. The fourth key finding is that the left angular gyrus seems to be critical in the production of motor actions directed towards the body. The fifth key finding is that performance on pantomime is strongly correlated with the severity of semantic deficits. Taken together, these findings invite us to offer a neurocognitive model of pantomime, which provides an integrated alternative to the two hypotheses that dominate the field: The gesture-engram hypothesis and the communicative hypothesis. More specifically, this model assumes that technical reasoning (notably the left area PF), the motor-control system (notably the intraparietal sulcus), body structural description (notably the left angular gyrus), semantic knowledge (notably the polar temporal lobes) and potentially theory of mind (notably the middle prefrontal cortex) work in concert to produce pantomime. The original features of this model open new avenues for understanding the neurocognitive bases of pantomime, emphasizing that pantomime is a communicative task that nevertheless originates in specific tool-use (not motor-related) cognitive processes. .

Suggestions for Improving the Investigation of Gesture in Aphasia

Purpose When we speak, we gesture, and indeed, persons with aphasia gesture more frequently. The reason(s) for this is still being investigated, spurring an increase in the number of studies of gesture in persons with aphasia. As the number of studies increases, so too does the need for a shared set of best practices for gesture research in aphasia. After briefly reviewing the importance and use of gesture in persons with aphasia, this viewpoint puts forth methodological and design considerations when evaluating gesture in persons with aphasia. Method & Results We explore several different design and methodological considerations for gesture research specific to persons with aphasia, such as video angle specifications, data collection techniques, and analysis considerations. The goal of these suggestions is to develop transparent and reproducible methods for evaluating gesture in aphasia to build a solid foundation for continued work in this area. Conclusions We have proposed that it is critical to evaluate multimodal communication in a methodologically robust way to facilitate increased knowledge about the relationship of gesture to spoken language, cognition, and to other aspects of living with aphasia and recovery from aphasia. We conclude by postulating future directions for gesture research in aphasia.

Nonverbal Semantics Test (NVST)-A Novel Diagnostic Tool to Assess Semantic Processing Deficits: Application to Persons with Aphasia after Cerebrovascular Accident

Assessment of semantic processing capacities often relies on verbal tasks which are, however, sensitive to impairments at several language processing levels. Especially for persons with aphasia there is a strong need for a tool that measures semantic processing skills independent of verbal abilities. Furthermore, in order to assess a patient’s potential for using alternative means of communication in cases of severe aphasia, semantic processing should be assessed in different nonverbal conditions. The Nonverbal Semantics Test (NVST) is a tool that captures semantic processing capacities through three tasks—Semantic Sorting, Drawing, and Pantomime. The main aim of the current study was to investigate the relationship between the NVST and measures of standard neurolinguistic assessment. Fifty-one persons with aphasia caused by left hemisphere brain damage were administered the NVST as well as the Aachen Aphasia Test (AAT). A principal component analysis (PCA) was conducted across all AAT and NVST subtests. The analysis resulted in a two-factor model that captured 69% of the variance of the original data, with all linguistic tasks loading high on one factor and the NVST subtests loading high on the other. These findings suggest that nonverbal tasks assessing semantic processing capacities should be administered alongside standard neurolinguistic aphasia tests.

The City Gesture Checklist: The development of a novel gesture assessment

BACKGROUND

People with aphasia rely on gesture more than healthy controls to get their message across, but use a limited range of gesture types. Gesture therapy is thus a potential avenue of intervention for people with aphasia. However, currently no gesture assessment evaluates how they use gesture. Such a tool could inform therapy targets and measure outcomes. In gesture research, many different coding categories are used to describe gesture forms and functions. These coding methods are prohibitively time-consuming to use in clinical practice. There is therefore a need for a 'quick and dirty' method of assessing gesture use.

AIMS

To investigate current practice among UK-based clinicians (speech and language therapists) in relation to gesture assessment and therapy, to synthesize gesture-coding frameworks used in aphasia research, to develop a gesture checklist based on the synthesized coding frameworks suitable for use in clinical practice, and to investigate the interrater reliability (IRR) of the checklist among experienced and unfamiliar users.

METHODS & PROCEDURES

The research team synthesized seven gesture-coding frameworks and trialled three resulting prototype checklists at a co-design workshop with 20 clinicians. Attending clinicians were also consulted about their current clinical gesture practice using a questionnaire. A final City Gesture Checklist (CGC) was developed based upon outcomes and feedback from the workshop. The IRR of the CGC was evaluated between the research team and 11 further clinicians within a second workshop. Both groups used the CGC to count gestures in video clips of people with aphasia talking to a conversation partner.

MAIN CONTRIBUTION

A total of 18 workshop attendees completed the current practice questionnaire. Of these, 10 reported assessing gesture informally and five also used formal assessment. Gesture-coding synthesis highlighted six main categories of gesture form. Clinicians at the co-design workshop provided feedback on prototype checklists regarding the relevance and usability of the gesture categories, layout, use of images and instructions. A final version of the CGC was created incorporating their recommendations. The IRR for the CGC was moderate between both the researchers and clinicians.

CONCLUSIONS & IMPLICATIONS

The CGC can be used to assess the types of gesture that people with aphasia produce. The IRR was moderate amongst both experienced users and new users who had received no training. Future research directions include investigating how to improve IRR, evaluating intra-rater reliability and sensitivity to change, and exploring use of the CGC in clinical practice. What this paper adds What is already known on the subject People with aphasia rely on gesture more than healthy speakers, yet use a more limited range of gesture types. Gesture therapy is used by clinicians with the aim of helping people with aphasia to compensate for their language impairment and/or to facilitate speech. What this paper adds to existing knowledge This study explores current gesture assessment practice among UK-based clinicians and synthesizes the coding categories used in the literature about gesture research in aphasia. It describes the development of a novel outcome measure, the CGC, and preliminary testing of its IRR. What are the potential or actual clinical implications of this work? This 'quick and dirty' tool enables clinicians to analyse and record the types of gesture produced by people with aphasia without the need for gesture coding. Preliminary findings suggest that clinicians can use it with a fair degree of reliability by following the checklist's written instructions.

An investigation into the relationship between Quality of pantomime gestures and visuospatial skills

While children with developmental language disorder or Williams syndrome appear to use hand gestures to compensate for specific cognitive and communicative difficulties, they have different cognitive strength-weakness profiles. Their semantic and visuospatial skills potentially affect gesture quality such as iconicity. The present study focuses on untangling the unique contribution of these skills in the quality of gestures. An explicit gesture elicitation task was presented to 25 participants with developmental language disorder between 7 and 10 years of age, 25 age-matched peers with typical development, and 14 participants with Williams Syndrome (8-23 years). They gestured pictures of objects without using speech (pantomime). The iconicity, semantic richness, and representation technique of the pantomimes were coded. Participants' semantic association and visuospatial skills were formally assessed. Iconicity was slightly lower in individuals with Williams syndrome, which seems related to their visuospatial deficit. While semantic saliency was similar across participant groups, small differences in representation technique were found. Partial correlations showed that visuospatial skills and semantic skills were instrumental in producing clear pantomimes. These findings indicate that clinicians aiming to enhance individuals' natural iconic gestures should consider achieved iconicity, particularly in individuals with low visuospatial skills.

Evaluating Models of Gesture and Speech Production for People With Aphasia

People with aphasia use gestures not only to communicate relevant content but also to compensate for their verbal limitations. The Sketch Model (De Ruiter, 2000) assumes a flexible relationship between gesture and speech with the possibility of a compensatory use of the two modalities. In the successor of the Sketch Model, the AR-Sketch Model (De Ruiter, 2017), the relationship between iconic gestures and speech is no longer assumed to be flexible and compensatory, but instead iconic gestures are assumed to express information that is redundant to speech. In this study, we evaluated the contradictory predictions of the Sketch Model and the AR-Sketch Model using data collected from people with aphasia as well as a group of people without language impairment. We only found compensatory use of gesture in the people with aphasia, whereas the people without language impairments made very little compensatory use of gestures. Hence, the people with aphasia gestured according to the prediction of the Sketch Model, whereas the people without language impairment did not. We conclude that aphasia fundamentally changes the relationship of gesture and speech.

The Role of Gesture in Communication and Cognition: Implications for Understanding and Treating Neurogenic Communication Disorders

When people talk, they gesture. Gesture is a fundamental component of language that contributes meaningful and unique information to a spoken message and reflects the speaker's underlying knowledge and experiences. Theoretical perspectives of speech and gesture propose that they share a common conceptual origin and have a tightly integrated relationship, overlapping in time, meaning, and function to enrich the communicative context. We review a robust literature from the field of psychology documenting the benefits of gesture for communication for both speakers and listeners, as well as its important cognitive functions for organizing spoken language, and facilitating problem-solving, learning, and memory. Despite this evidence, gesture has been relatively understudied in populations with neurogenic communication disorders. While few studies have examined the rehabilitative potential of gesture in these populations, others have ignored gesture entirely or even discouraged its use. We review the literature characterizing gesture production and its role in intervention for people with aphasia, as well as describe the much sparser literature on gesture in cognitive communication disorders including right hemisphere damage, traumatic brain injury, and Alzheimer's disease. The neuroanatomical and behavioral profiles of these patient populations provide a unique opportunity to test theories of the relationship of speech and gesture and advance our understanding of their neural correlates. This review highlights several gaps in the field of communication disorders which may serve as a bridge for applying the psychological literature of gesture to the study of language disorders. Such future work would benefit from considering theoretical perspectives of gesture and using more rigorous and quantitative empirical methods in its approaches. We discuss implications for leveraging gesture to explore its untapped potential in understanding and rehabilitating neurogenic communication disorders.

Charlie Chaplin and gesture training in severe aphasia: A controlled double-blind single-case experimental design

BACKGROUND

Aphasia following a stroke is a frequent and disabling condition that decreases quality of life. The use of gesture has been proposed as a way to enhance aphasia recovery.

OBJECTIVE

We aimed to explore whether 2 types of gesture interventions could improve communication in individuals with severe aphasia.

METHODS

This was a pilot study performed at home in routine care by an outreach team. The study had a controlled double-blind single-case experimental design (SCED): a controlled multiple baseline design across 3 participants and 2 behaviors (gesture and naming). Three male patients with stroke-induced severe chronic aphasia, non-functional perseverative speech and severe associated impairments underwent a passive gesture intervention, in which participants watched movies selected for their intensive use of gesture, and an active gesture intervention, in which they actively practiced gestures by using visual action therapy. The main outcome measures were naming score, gesture score and nonverbal subscale score of the Lillois Test of Communication, with 3-month follow-up.

RESULTS

In all 3 participants, gesture interventions improved the ability to gesture a list of words (Tau-U=0.38-0.67 for combined gesture intervention effect) and increased nonverbal communication activity. Benefits were maintained at 3-month follow-up.

CONCLUSIONS

Mute films that use intensive nonverbal communication may be a useful add-on to speech therapy for individuals with aphasia. Improving naming in severe and chronic aphasia may not be feasible, and more effort could be devoted to improving gesture-based and nonverbal communication.

A description of verbal and gestural communication during postictal aphasia

Patients suffering from drug-resistant temporal lobe epilepsy show substantial language deficits (i.e., anomia) during their seizures and in the postictal period (postictal aphasia). Verbal impairments observed during the postictal period may be studied to help localizing the epileptogenic zone. These explorations have been essentially based on simple tasks focused on speech, thus disregarding the multimodal nature of verbal communication, particularly the fact that, when speakers want to communicate, they often produce gestures of various kinds. Here, we propose an innovative procedure for testing postictal language and communication abilities, including the assessment of co-speech gestures. We provide a preliminary description of the changes induced on communication during postictal aphasia. We studied 21 seizures that induced postictal aphasia from 12 patients with drug-refractory epilepsy, including left temporal and left frontal seizures. The experimental task required patients to memorize a highly detailed picture and, briefly after, to describe what they had seen, thus eliciting a communicative meaningful monologue. This allowed comparing verbal communication in postictal and interictal conditions within the same individuals. Co-speech gestures were coded according to two categories: "Rhythmic" gestures, thought to be produced in support of speech building, and "illustrative" gestures, thought to be produced to complement the speech content. When postictal and interictal conditions were compared, there was decreased speech flow along with an increase of rhythmic gesture production at the expense of illustrative gesture production. The communication patterns did not differ significantly after temporal and frontal seizures, yet they were illustrated separately, owing to the clinical importance of the distinction, along with considerations of interindividual variability. A contrast between rhythmic and illustrative gestures production is congruent with previous literature in which rhythmic gestures have been linked to lexical retrieval processes. If confirmed in further studies, such evidence for a facilitative role of co-speech gestures in language difficulties could be put to use in the context of multimodal language therapies.

Multimodality and the origin of a novel communication system in face-to-face interaction

Face-to-face communication is multimodal at its core: it consists of a combination of vocal and visual signalling. However, current evidence suggests that, in the absence of an established communication system, visual signalling, especially in the form of visible gesture, is a more powerful form of communication than vocalization and therefore likely to have played a primary role in the emergence of human language. This argument is based on experimental evidence of how vocal and visual modalities (i.e. gesture) are employed to communicate about familiar concepts when participants cannot use their existing languages. To investigate this further, we introduce an experiment where pairs of participants performed a referential communication task in which they described unfamiliar stimuli in order to reduce reliance on conventional signals. Visual and auditory stimuli were described in three conditions: using visible gestures only, using non-linguistic vocalizations only and given the option to use both (multimodal communication). The results suggest that even in the absence of conventional signals, gesture is a more powerful mode of communication compared with vocalization, but that there are also advantages to multimodality compared to using gesture alone. Participants with an option to produce multimodal signals had comparable accuracy to those using only gesture, but gained an efficiency advantage. The analysis of the interactions between participants showed that interactants developed novel communication systems for unfamiliar stimuli by deploying different modalities flexibly to suit their needs and by taking advantage of multimodality when required.

The Production of Gesture and Speech by People With Aphasia: Influence of Communicative Constraints

Purpose People with aphasia (PWA) use different kinds of gesture spontaneously when they communicate. Although there is evidence that the nature of the communicative task influences the linguistic performance of PWA, so far little is known about the influence of the communicative task on the production of gestures by PWA. We aimed to investigate the influence of varying communicative constraints on the production of gesture and spoken expression by PWA in comparison to persons without language impairment. Method Twenty-six PWA with varying aphasia severities and 26 control participants (CP) without language impairment participated in the study. Spoken expression and gesture production were investigated in 2 different tasks: (a) spontaneous conversation about topics of daily living and (b) a cartoon narration task, that is, retellings of short cartoon clips. The frequencies of words and gestures as well as of different gesture types produced by the participants were analyzed and tested for potential effects of group and task. Results Main results for task effects revealed that PWA and CP used more iconic gestures and pantomimes in the cartoon narration task than in spontaneous conversation. Metaphoric gestures, deictic gestures, number gestures, and emblems were more frequently used in spontaneous conversation than in cartoon narrations by both participant groups. Group effects show that, in both tasks, PWA's gesture-to-word ratios were higher than those for the CP. Furthermore, PWA produced more interactive gestures than the CP in both tasks, as well as more number gestures and pantomimes in spontaneous conversation. Conclusions The current results suggest that PWA use gestures to compensate for their verbal limitations under varying communicative constraints. The properties of the communicative task influence the use of different gesture types in people with and without aphasia. Thus, the influence of communicative constraints needs to be considered when assessing PWA's multimodal communicative abilities.

Can gesture observation help people with aphasia name actions?

It has been suggested that gesture can play a role in the treatment of naming impairments in aphasia, however investigation is still sparse, especially when compared to research on verbal treatments. Critically, previous studies have included either verbal or gesture production in the training. However, while in speakers without language impairment, action naming is facilitated by gesture observation, no study has yet systematically determined whether gesture observation alone influences word retrieval in people with aphasia. This is the aim of the research presented here. In a gesture priming experiment, participants with aphasia named actions that were preceded by the observation of videos of congruent or unrelated gestures or a non-gesture control condition. At the group-level, action naming was facilitated by observation of congruent gestures. However, single-case analyses revealed variability in the extent to which the participants benefited from gesture cueing. The potential mechanisms underlying the effects of gesture observation on action picture naming in people with aphasia were examined by exploring participant-related and item-related predictors of improvement. It is concluded that gesture observation may facilitate verb retrieval at either semantic or lexical levels. In addition, and despite variability across individuals, gesture observation seems more likely to facilitate action naming in people with spared gesture semantics and mild-moderate deficits in lexical-semantic or post-semantic processing.

Differential roles of gestures on spatial language in neurotypical elderly adults and individuals with focal brain injury

Gestures might serve communicative functions by supplementing spoken expressions or restorative functions by facilitating speech production. Also, speakers with speech deficits use gestures to compensate for their speech impairments. In this study, we examined gesture use in speakers with and without speech impairments and how spoken spatial expressions changed when gestures were restrained. Six patients with speech problems and with left frontal and/or temporal lesions and 20 neurotypical controls described motion events in 3 different conditions (spontaneous gesture, only speech, and only gesture). In addition to the group analyses, we ran case analyses. Results showed that patients used more gestures compared to controls. Gestures served both communicative and restorative functions for patients whereas controls only used gestures for communicative purposes. Case analyses revealed that there were differential patterns among patients. Overall, gesture production is multifunctional and gestures serve different functions for different populations as well as within a population.

Language as a Predictor of Motor Recovery: The Case for a More Global Approach to Stroke Rehabilitation

Stroke is the third leading cause of death in the developed world and the primary cause of adult disability. The most common site of stroke is the middle cerebral artery (MCA), an artery that supplies a range of areas involved in both language and motor function. As a consequence, many stroke patients experience a combination of language and motor deficits. Indeed, those suffering from Broca's aphasia have an 80% chance of also suffering hemiplegia. Despite the prevalence of multifaceted disability in patients, the current trend in both clinical trials and clinical practice is toward compartmentalization of dysfunction. In this article, we review evidence that aphasia and hemiplegia do not just coexist, but that they interact. We review a number of clinical reports describing how therapies for one type of deficit can improve recovery in the other and vice versa. We go on to describe how language deficits should be seen as a warning to clinicians that the patient is likely to experience motor impairment and slower motor recovery, aiding clinicians to optimize their choice of therapy. We explore these findings and offer a tentative link between language and arm function through their shared need for sequential action, which we term fluency. We propose that area BA44 (part of Broca's area) acts as a hub for fluency in both movement and language, both in terms of production and comprehension.

The relationship between co-speech gesture production and macrolinguistic discourse abilities in people with focal brain injury

Brain damage is associated with linguistic deficits and might alter co-speech gesture production. Gesture production after focal brain injury has been mainly investigated with respect to intrasentential rather than discourse-level linguistic processing. In this study, we examined 1) spontaneous gesture production patterns of people with left hemisphere damage (LHD) or right hemisphere damage (RHD) in a narrative setting, 2) the neural structures associated with deviations in spontaneous gesture production in these groups, and 3) the relationship between spontaneous gesture production and discourse level linguistic processes (narrative complexity and evaluation competence). Individuals with LHD or RHD (17 people in each group) and neurotypical controls (n = 13) narrated a story from a picture book. Results showed that increase in gesture production for LHD individuals was associated with less complex narratives and lesions of individuals who produced more gestures than neurotypical individuals overlapped in frontal-temporal structures and basal ganglia. Co-speech gesture production of RHD individuals positively correlated with their evaluation competence in narrative. Lesions of RHD individuals who produced more gestures overlapped in the superior temporal gyrus and the inferior parietal lobule. Overall, LHD individuals produced more gestures than neurotypical individuals. The groups did not differ in their use of different gesture forms except that LHD individuals produced more deictic gestures per utterance than RHD individuals and controls. Our findings are consistent with the hypothesis that co-speech gesture production interacts with macro-linguistic levels of discourse and this interaction is affected by the hemispheric lateralization of discourse abilities.

Using Images With Individuals With Aphasia: Current Research and Clinical Trends

PURPOSE

Visuographic supports in the form of images are utilized during assessment and treatment for individuals with aphasia to supplement speech, language, and cognitive losses limiting communication. Clinicians rely on prior experience and intuition to make decisions regarding image-based support design and selection (e.g., augmentative and alternative communication strategies). Researchers have begun to focus on the relationship between the images and the benefits they provide for adults with aphasia.

METHOD

The aim of this review-resulting from a roundtable discussion at the 2016 Clinical Aphasiology Conference-was to disseminate summaries of current and past researches regarding image use by individuals with aphasia and to highlight areas of need within research and practice.

RESULTS

Review of the literature illuminated 4 major themes: (a) image creation, capture, and sharing; (b) image characteristics; (c) image use across linguistic domains and contexts; and (d) implications for clinical and research practices.

CONCLUSIONS

Reviewing current knowledge and practice regarding the use of visual supports for individuals with aphasia is essential to advancing therapeutic practices and providing evidence-based protocols for creating, selecting, and implementing images within augmentative and alternative communication strategies. Several gaps in knowledge were identified as future research needs (e.g., caregiver training and enhanced image feature investigation).

The comprehensibility of pantomimes produced by people with aphasia

BACKGROUND

People with aphasia (PWA) use pantomime, gesture in absence of speech, differently from non-brain-damaged people (NBDP).

AIMS

To evaluate through an exploratory study the comprehensibility of PWA's pantomimes and to find out whether they can compensate for information PWA are unable to convey in speech.

METHODS & PROCEDURES

A total of 273 naïve observers participated in one of two judgement tasks: forced-choice and open-ended questions. These were used to determine the comprehensibility of pantomimes produced to depict objects by PWA as compared with NBDP. Furthermore, we compared the information conveyed in pantomime with the information in speech. We looked into factors influencing pantomime's comprehensibility: individual factors, manner of depiction and information needed to be depicted.

OUTCOME & RESULTS

Although comprehensibility scores for PWA's pantomimes were lower than for those produced by NBDP, all PWA were able to convey information in pantomime that they could not convey in speech. Comprehensibility of pantomimes was predicted by apraxia. The inability to use the right hand related to slightly lower comprehensibility scores. Objects for which individuals depicted its use were best understood.

CONCLUSION & IMPLICATIONS

Our findings highlight the potential benefit of pantomime for clinical practice. Pantomimes, even though sometimes impaired, can convey information that PWA cannot convey in speech. Clinical implications are discussed.

Comprehensibility and neural substrate of communicative gestures in severe aphasia

Communicative gestures can compensate incomprehensibility of oral speech in severe aphasia, but the brain damage that causes aphasia may also have an impact on the production of gestures. We compared the comprehensibility of gestural communication of persons with severe aphasia and non-aphasic persons and used voxel based lesion symptom mapping (VLSM) to determine lesion sites that are responsible for poor gestural expression in aphasia. On group level, persons with aphasia conveyed more information via gestures than controls indicating a compensatory use of gestures in persons with severe aphasia. However, individual analysis showed a broad range of gestural comprehensibility. VLSM suggested that poor gestural expression was associated with lesions in anterior temporal and inferior frontal regions. We hypothesize that likely functional correlates of these localizations are selection of and flexible changes between communication channels as well as between different types of gestures and between features of actions and objects that are expressed by gestures.

How Much Information Do People With Aphasia Convey via Gesture?

PURPOSE

People with aphasia (PWA) face significant challenges in verbally expressing their communicative intentions. Different types of gestures are produced spontaneously by PWA, and a potentially compensatory function of these gestures has been discussed. The current study aimed to investigate how much information PWA communicate through 3 types of gesture and the communicative effectiveness of such gestures.

METHOD

Listeners without language impairment rated the information content of short video clips taken from PWA in conversation. Listeners were asked to rate communication within a speech-only condition and a gesture + speech condition.

RESULTS

The results revealed that the participants' interpretations of the communicative intentions expressed in the clips of PWA were significantly more accurate in the gesture + speech condition for all tested gesture types.

CONCLUSION

It was concluded that all 3 gesture types under investigation contributed to the expression of semantic meaning communicated by PWA. Gestures are an important communicative means for PWA and should be regarded as such by their interlocutors. Gestures have been shown to enhance listeners' interpretation of PWA's overall communication.

Communicative effectiveness of pantomime gesture in people with aphasia

BACKGROUND

Human communication occurs through both verbal and visual/motoric modalities. Simultaneous conversational speech and gesture occurs across all cultures and age groups. When verbal communication is compromised, more of the communicative load can be transferred to the gesture modality. Although people with aphasia produce meaning-laden gestures, the communicative value of these has not been adequately investigated.

AIMS

To investigate the communicative effectiveness of pantomime gesture produced spontaneously by individuals with aphasia during conversational discourse.

METHODS & PROCEDURES

Sixty-seven undergraduate students wrote down the messages conveyed by 11 people with aphasia that produced pantomime while engaged in conversational discourse. Students were presented with a speech-only, a gesture-only and a combined speech and gesture condition and guessed messages in both a free description and a multiple-choice task.

OUTCOMES & RESULTS

As hypothesized, listener comprehension was more accurate in the combined pantomime gesture and speech condition as compared with the gesture- or speech-only conditions. Participants achieved greater accuracy in the multiple-choice task as compared with the free-description task, but only in the gesture-only condition. The communicative effectiveness of the pantomime gestures increased as the fluency of the participants with aphasia decreased.

CONCLUSIONS & IMPLICATIONS

These results indicate that when pantomime gesture was presented with aphasic speech, the combination had strong communicative effectiveness. Future studies could investigate how pantomimes can be integrated into interventions for people with aphasia, particularly emphasizing elicitation of pantomimes in as natural a context as possible and highlighting the opportunity for efficient message repair.

Facets of Pantomime

OBJECTIVES

Exploring the nature of defective pantomime in apraxia.

METHODS

Critical review of behavioral associations and dissociations between defective pantomime, imitation of gestures, and real tool use. Analysis of congruencies between crucial lesions for pantomime, imitation, and tool use.

RESULTS

There are behavioral double dissociations between pantomime and imitation, and their cerebral substrates show very little overlap. Whereas defective pantomime is bound to temporal and inferior frontal lesions, imitation is mainly affected by parietal lesions. Pantomime usually replicates the motor actions of real use but on scrutiny there are important differences between the movements of real use and of pantomime that cast doubt on the assumption that pantomime is produced by the same motor programs as actual use. A more plausible proposal posits that pantomime is a communicative gesture that uses manual actions for conveying information about objects and their use. The manual actions are constructed by selection and combination of distinctive features of tools and actions. They frequently include replications of characteristic motor actions of real use, but the main criterion for selection and modification of features is the comprehensibility of the gestures rather than the accurate replication of the motor actions of real use.

CONCLUSIONS

Pantomime of tool use is a communicative gesture rather than a replication of the motor actions of real use. (JINS, 2017, 23, 121-127).

Benefits and Limitations of Computer Gesture Therapy for the Rehabilitation of Severe Aphasia

Aphasia intervention has made increasing use of technology in recent years. The evidence base, which is largely limited to the investigation of spoken language outcomes, indicates positive treatment effects for people with mild to moderate levels of aphasia. Outcomes for those with severe aphasia, however, are less well documented and – where reported – present less consistent gains for measures of spoken output. This study investigates the effects of a purpose-built gesture therapy technology for people with severe aphasia: GeST+. Study outcomes show significant improvement in gesture production abilities for adults with severe aphasia following computer intervention. They indicate no transfer of effects into naming gains or interactive gesture. Outcomes offer encouraging results for computer therapy methods within this hitherto under-researched population but indicate a need for further refinement of interventions in order to maximize persistence of effects and generalization into everyday communication.

Pantomime Production by People With Aphasia: What Are Influencing Factors?

PURPOSE

The present article aimed to inform clinical practice on whether people with aphasia (PWA) deploy pantomime techniques similarly to participants without brain damage (PWBD) and if not, what factors influence these differences.

METHOD

We compared 38 PWA to 20 PWBD in their use of 6 representation techniques (handling, enact, object, shape, deictic, and other) when pantomiming objects, and determined whether PWA used the same defaults as PWBD. We assessed the influence of (non-)dominant arm use, ideomotor apraxia, semantic processing, aphasia severity, and oral naming.

RESULTS

PWA used various pantomime techniques. Enact, deictic, and other were used infrequently. No differences were found for the use of shape techniques, but PWA used fewer handling and object techniques than PWBD and they did not use these for the same objects as PWBD did. No influence was found for (non-)dominant arm use. All other variables correlated with the use of handling, object, and defaults.

CONCLUSION

In our study, PWA were able to use various pantomime techniques. As a group, they used these techniques differently from PWBD and relied more heavily on the use of shape techniques. This was not influenced by a hemiparesis, but seemed dependent on semantic processing. Clinical implications are discussed.

Comprehension of Co-Speech Gestures in Aphasic Patients: An Eye Movement Study

BACKGROUND

Co-speech gestures are omnipresent and a crucial element of human interaction by facilitating language comprehension. However, it is unclear whether gestures also support language comprehension in aphasic patients. Using visual exploration behavior analysis, the present study aimed to investigate the influence of congruence between speech and co-speech gestures on comprehension in terms of accuracy in a decision task.

METHOD

Twenty aphasic patients and 30 healthy controls watched videos in which speech was either combined with meaningless (baseline condition), congruent, or incongruent gestures. Comprehension was assessed with a decision task, while remote eye-tracking allowed analysis of visual exploration.

RESULTS

In aphasic patients, the incongruent condition resulted in a significant decrease of accuracy, while the congruent condition led to a significant increase in accuracy compared to baseline accuracy. In the control group, the incongruent condition resulted in a decrease in accuracy, while the congruent condition did not significantly increase the accuracy. Visual exploration analysis showed that patients fixated significantly less on the face and tended to fixate more on the gesturing hands compared to controls.

CONCLUSION

Co-speech gestures play an important role for aphasic patients as they modulate comprehension. Incongruent gestures evoke significant interference and deteriorate patients' comprehension. In contrast, congruent gestures enhance comprehension in aphasic patients, which might be valuable for clinical and therapeutic purposes.

Language and iconic gesture use in procedural discourse by speakers with aphasia

Background: Conveying instructions is an everyday use of language, and gestures are likely to be a key feature of this. Although co-speech iconic gestures are tightly integrated with language, and people with aphasia (PWA) produce procedural discourses impaired at a linguistic level, no previous studies have investigated how PWA use co-speech iconic gestures in these contexts. Aims: This study investigated how PWA communicated meaning using gesture and language in procedural discourses, compared with neurologically healthy people (NHP). We aimed to identify the relative relationship of gesture and speech, in the context of impaired language, both overall and in individual events. Methods & Procedures: Twenty-nine PWA and 29 NHP produced two procedural discourses. The structure and semantic content of language of the whole discourses were analysed through predicate argument structure and spatial motor terms, and gestures were analysed for frequency and semantic form. Gesture and language were analysed in two key events, to determine the relative information presented in each modality. Outcomes & Results: PWA and NHP used similar frequencies and forms of gestures, although PWA used syntactically simpler language and fewer spatial words. This meant, overall, relatively more information was present in PWA gesture. This finding was also reflected in the key events, where PWA used gestures conveying rich semantic information alongside semantically impoverished language more often than NHP. Conclusions: PWA gestures, containing semantic information omitted from the concurrent speech, may help listeners with meaning when language is impaired. This finding indicates gesture should be included in clinical assessments of meaning-making.

Co-verbal gestures among speakers with aphasia: Influence of aphasia severity, linguistic and semantic skills, and hemiplegia on gesture employment in oral discourse

The use of co-verbal gestures is common in human communication and has been reported to assist word retrieval and to facilitate verbal interactions. This study systematically investigated the impact of aphasia severity, integrity of semantic processing, and hemiplegia on the use of co-verbal gestures, with reference to gesture forms and functions, by 131 normal speakers, 48 individuals with aphasia and their controls. All participants were native Cantonese speakers. It was found that the severity of aphasia and verbal-semantic impairment was associated with significantly more co-verbal gestures. However, there was no relationship between right-sided hemiplegia and gesture employment. Moreover, significantly more gestures were employed by the speakers with aphasia, but about 10% of them did not gesture. Among those who used gestures, content-carrying gestures, including iconic, metaphoric, deictic gestures, and emblems, served the function of enhancing language content and providing information additional to the language content. As for the non-content carrying gestures, beats were used primarily for reinforcing speech prosody or guiding speech flow, while non-identifiable gestures were associated with assisting lexical retrieval or with no specific functions. The above findings would enhance our understanding of the use of various forms of co-verbal gestures in aphasic discourse production and their functions. Speech-language pathologists may also refer to the current annotation system and the results to guide clinical evaluation and remediation of gestures in aphasia.

LEARNING OUTCOMES

None.

The language-gesture connection: Evidence from aphasia

A significant body of evidence from cross-linguistic and developmental studies converges to suggest that co-speech iconic gesture mirrors language. This paper aims to identify whether gesture reflects impaired spoken language in a similar way. Twenty-nine people with aphasia (PWA) and 29 neurologically healthy control participants (NHPs) produced a narrative discourse, retelling the story of a cartoon video. Gesture and language were analysed in terms of semantic content and structure for two key motion events. The aphasic data showed an influence on gesture from lexical choices but no corresponding clausal influence. Both the groups produced gesture that matched the semantics of the spoken language and gesture that did not, although there was one particular gesture-language mismatch (semantically "light" verbs paired with semantically richer gesture) that typified the PWA narratives. These results indicate that gesture is both closely related to spoken language impairment and compensatory.

Tool use disorders after left brain damage

In this paper we review studies that investigated tool use disorders in left-brain damaged (LBD) patients over the last 30 years. Four tasks are classically used in the field of apraxia: Pantomime of tool use, single tool use, real tool use and mechanical problem solving. Our aim was to address two issues, namely, (1) the role of mechanical knowledge in real tool use and (2) the cognitive mechanisms underlying pantomime of tool use, a task widely employed by clinicians and researchers. To do so, we extracted data from 36 papers and computed the difference between healthy subjects and LBD patients. On the whole, pantomime of tool use is the most difficult task and real tool use is the easiest one. Moreover, associations seem to appear between pantomime of tool use, real tool use and mechanical problem solving. These results suggest that the loss of mechanical knowledge is critical in LBD patients, even if all of those tasks (and particularly pantomime of tool use) might put differential demands on semantic memory and working memory.

The tool in the brain: apraxia in ADL. Behavioral and neurological correlates of apraxia in daily living

Humans differ from other animals in the way they can skilfully and precisely operate or invent tools to facilitate their everyday life. Tools have dominated our home, travel and work environment, becoming an integral step for our motor skills development. What happens when the part of the brain responsible for tool use is damaged in our adult life due to a cerebrovascular accident? How does daily life change when we lose the previously mastered ability to make use of the objects around us? How do patients suffering from compromised tool use cope with food preparation, personal hygiene, grooming, housework, or use of home appliances? In this literature review we present a state of the art for single and multiple tool use research, with a focus on the impact that apraxia (impaired ability to perform tool-based actions) and action disorganization syndrome (ADS; impaired ability to carry out multi-step actions) have on activities of daily living (ADL). Firstly, we summarize the behavioral studies investigating the impact of apraxia and other comorbidity syndromes, such as neglect or visual extinction, on ADL. We discuss the hallmarks of the compromised tool use in terms of the sequencing of action steps, conceptual errors committed, spatial motor control, and temporal organization of the movement. In addition, we present an up-to-date overview of the neuroimaging and lesion analyses studies that provide an insight into neural correlates of tool use in the human brain and functional changes in the neural organization following a stroke, in the context of ADL. Finally we discuss the current practice in neurorehabilitation of ADL in apraxia and ADS aiming at increasing patients' independence.

The relationship of aphasia type and gesture production in people with aphasia

PURPOSE

For many individuals with aphasia, gestures form a vital component of message transfer and are the target of speech-language pathology intervention. What remains unclear are the participant variables that predict successful outcomes from gesture treatments. The authors examined the gesture production of a large number of individuals with aphasia-in a consistent discourse sampling condition and with a detailed gesture coding system-to determine patterns of gesture production associated with specific types of aphasia.

METHOD

The authors analyzed story retell samples from AphasiaBank (TalkBank, n.d.), gathered from 98 individuals with aphasia resulting from stroke and 64 typical controls. Twelve gesture types were coded. Descriptive statistics were used to describe the patterns of gesture production. Possible significant differences in production patterns according to aphasia type were examined using a series of chi-square, Fisher exact, and logistic regression statistics.

RESULTS

A significantly higher proportion of individuals with aphasia gestured as compared to typical controls, and for many individuals with aphasia, this gesture was iconic and was capable of communicative load. Aphasia type impacted significantly on gesture type in specific identified patterns, detailed here.

CONCLUSION

These type-specific patterns suggest the opportunity for gestures as targets of aphasia therapy.

The impact of impaired semantic knowledge on spontaneous iconic gesture production

BACKGROUND

Previous research has found that people with aphasia produce more spontaneous iconic gesture than control participants, especially during word-finding difficulties. There is some evidence that impaired semantic knowledge impacts on the diversity of gestural handshapes, as well as the frequency of gesture production. However, no previous research has explored how impaired semantic knowledge impacts on the frequency and type of iconic gestures produced during fluent speech compared with those produced during word-finding difficulties.

AIMS

To explore the impact of impaired semantic knowledge on the frequency and type of iconic gestures produced during fluent speech and those produced during word-finding difficulties.

METHODS & PROCEDURES

A group of 29 participants with aphasia and 29 control participants were video recorded describing a cartoon they had just watched. All iconic gestures were tagged and coded as either "manner," "path only," "shape outline" or "other". These gestures were then separated into either those occurring during fluent speech or those occurring during a word-finding difficulty. The relationships between semantic knowledge and gesture frequency and form were then investigated in the two different conditions.

OUTCOMES & RESULTS

As expected, the participants with aphasia produced a higher frequency of iconic gestures than the control participants, but when the iconic gestures produced during word-finding difficulties were removed from the analysis, the frequency of iconic gesture was not significantly different between the groups. While there was not a significant relationship between the frequency of iconic gestures produced during fluent speech and semantic knowledge, there was a significant positive correlation between semantic knowledge and the proportion of word-finding difficulties that contained gesture. There was also a significant positive correlation between the speakers' semantic knowledge and the proportion of gestures that were produced during fluent speech that were classified as "manner". Finally while not significant, there was a positive trend between semantic knowledge of objects and the production of "shape outline" gestures during word-finding difficulties for objects.

CONCLUSIONS

The results indicate that impaired semantic knowledge in aphasia impacts on both the iconic gestures produced during fluent speech and those produced during word-finding difficulties but in different ways. These results shed new light on the relationship between impaired language and iconic co-speech gesture production and also suggest that analysis of iconic gesture may be a useful addition to clinical assessment.

Lexical learning in mild aphasia: gesture benefit depends on patholinguistic profile and lesion pattern

Gestures accompany speech and enrich human communication. When aphasia interferes with verbal abilities, gestures become even more relevant, compensating for and/or facilitating verbal communication. However, small-scale clinical studies yielded diverging results with regard to a therapeutic gesture benefit for lexical retrieval. Based on recent functional neuroimaging results, delineating a speech-gesture integration network for lexical learning in healthy adults, we hypothesized that the commonly observed variability may stem from differential patholinguistic profiles in turn depending on lesion pattern. Therefore we used a controlled novel word learning paradigm to probe the impact of gestures on lexical learning, in the lesioned language network. Fourteen patients with chronic left hemispheric lesions and mild residual aphasia learned 30 novel words for manipulable objects over four days. Half of the words were trained with gestures while the other half were trained purely verbally. For the gesture condition, rootwords were visually presented (e.g., Klavier, [piano]), followed by videos of the corresponding gestures and the auditory presentation of the novel words (e.g., /krulo/). Participants had to repeat pseudowords and simultaneously reproduce gestures. In the verbal condition no gesture-video was shown and participants only repeated pseudowords orally. Correlational analyses confirmed that gesture benefit depends on the patholinguistic profile: lesser lexico-semantic impairment correlated with better gesture-enhanced learning. Conversely largely preserved segmental-phonological capabilities correlated with better purely verbal learning. Moreover, structural MRI-analysis disclosed differential lesion patterns, most interestingly suggesting that integrity of the left anterior temporal pole predicted gesture benefit. Thus largely preserved semantic capabilities and relative integrity of a semantic integration network are prerequisites for successful use of the multimodal learning strategy, in which gestures may cause a deeper semantic rooting of the novel word-form. The results tap into theoretical accounts of gestures in lexical learning and suggest an explanation for the diverging effect in therapeutical studies advocating gestures in aphasia rehabilitation.

Gesturing by speakers with aphasia: how does it compare?

PURPOSE

To study the independence of gesture and verbal language production. The authors assessed whether gesture can be semantically compensatory in cases of verbal language impairment and whether speakers with aphasia and control participants use similar depiction techniques in gesture.

METHOD

The informativeness of gesture was assessed in 3 forced-choice studies, in which raters assessed the topic of the speaker's message in video clips of 13 speakers with moderate aphasia and 12 speakers with severe aphasia, who were performing a communication test (the Scenario Test). Both groups were compared and contrasted with 17 control participants, who either were or were not allowed to communicate verbally. In addition, the representation techniques used in gesture were analyzed.

RESULTS

Gestures produced by speakers with more severe aphasia were less informative than those by speakers with moderate aphasia, yet they were not necessarily uninformative. Speakers with more severe aphasia also tended to use fewer representation techniques (mostly relying on outlining gestures) in co-speech gesture than control participants, who were asked to use gesture instead of speech. It is important to note that limb apraxia may be a mediating factor here.

CONCLUSIONS

These results suggest that in aphasia, gesture tends to degrade with verbal language. This may imply that the processes underlying verbal language and co-speech gesture production, although partly separate, are closely linked.