Heather Harris Wright

Processing distinct linguistic information types in working memory in aphasia

Background: Recent investigations have suggested that adults with aphasia present with a working memory deficit that may contribute to their language‐processing difficulties. Working memory capacity has been conceptualised as a single “resource” pool for attentional, linguistic, and other executive processing—alternatively, it has been suggested that there may be separate working memory abilities for different types of linguistic information. A challenge in this line of research is developing an appropriate measure of working memory ability in adults with aphasia. One candidate measure of working memory ability that may be appropriate for this population is the n‐back task. By manipulating stimulus type, the n‐back task may be appropriate for tapping linguistic‐specific working memory abilities. Aims: The purposes of this study were (a) to measure working memory ability in adults with aphasia for processing specific types of linguistic information, and (b) to examine whether a relationship exists between participants performance on working memory and auditory comprehension measures. Method & Procedures: Nine adults with aphasia participated in the study. Participants completed three n‐back tasks, each tapping different types of linguistic information. They included the PhonoBack (phonological level), SemBack (semantic level), and SynBack (syntactic level). For all tasks, two n‐back levels were administered: a 1‐back and 2‐back. Each level contained 20 target items; accuracy was recorded by stimulus presentation software. The Subject‐relative, Object‐relative, Active, Passive Test of Syntactic Complexity (SOAP) was the syntactic sentence comprehension task administered to all participants. Outcomes & Results: Participants performance declined as n‐back task difficulty increased. Overall, participants performed better on the SemBack than PhonoBack and SynBack tasks, but the differences were not statistically significant. Finally, participants who performed poorly on the SynBack also had more difficulty comprehending syntactically complex sentence structures (i.e., passive & object‐relative sentences). Conclusions: Results indicate that working memory ability for different types of linguistic information can be measured in adults with aphasia. Further, our results add to the growing literature that favours separate working memory abilities for different types of linguistic information view.

Verbal and non-verbal working memory in aphasia: What three n-back tasks reveal

Background: Researchers have found that many individuals with aphasia (IWA) present with cognitive deficits that may impact their communication, and perhaps underlie their language-processing deficits (e.g., Erickson et al., 1996; Murray et al., 1997; Wright et al., 2003). However, many investigations of cognitive ability in aphasia have included measures that may be considered “language heavy”; they require overt lexical, semantic, and/or phonological processing to follow the task instructions and/or formulate a response. Few have considered the amount of linguistic processing required to perform the task. Subsequently, it is not clear if poorer performance by IWA on cognitive tasks compared to neurologically intact (NI) participants is due to a deficit in the respective cognitive domain or due to the inability of IWA to perform the task because of their language difficulties. Aims: The purpose of the current study was to explore the effect of varying linguistic processing demands in the context of a dynamic working memory task—an n-back task for participants with and without aphasia. Method & Procedures: This study compared differences on three different n-back tasks within and across groups for individuals with aphasia and NI matched peers. Participants completed three different n-back tasks; stimuli for the tasks varied in “linguistic load”. For each n-back task participants completed two levels of difficulty: 1-back and 2-back. Outcomes & Results: The aphasia group performed significantly worse than the NI participants across the n-back tasks. All participants performed significantly better with the stimuli that carried a higher linguistic load (i.e., the fruit), than with the fribbles (semi-linguistic) and blocks (non-linguistic). All participants performed significantly better on the 1-back than the 2-back working memory task. Unlike the NI participants, IWA performed equally poorly with the fribbles and the blocks in the 2-back task. Conclusions: Overall, the performance of individuals with aphasia on working memory tasks that varied in their linguistic load was similar to the control group but reduced. However, unlike the NI participants, IWA were less skilled at rapidly utilising linguistic knowledge to increase performance on the fribbles, demonstrating the further decrement in working memory that results from a decreased ability to utilise a linguistic strategy to increase performance on verbal working memory tasks. The results of this study indicate that language ability has a significant influence on performance on working memory tasks and should be considered when discussing cognitive deficits in aphasia.

Conceptualising and measuring working memory and its relationship to aphasia

Background: General agreement exists in the literature that individuals with aphasia can exhibit a working memory deficit that contributes to their language-processing impairments. Although conceptualised within different working memory frameworks, researchers have suggested that individuals with aphasia have limited working memory capacity and impaired attention-control processes as well as impaired inhibitory mechanisms. However, across studies investigating working memory ability in individuals with aphasia, different measures have been used to quantify their working memory ability and identify the relationship between working memory and language performance. Aims: The primary objectives of this article are (1) to review current working memory theoretical frameworks, (2) to review tasks used to measure working memory, and (3) to discuss findings from studies that have investigated working memory as they relate to language processing in aphasia. Main Contribution: Although findings have been consistent across studies investigating working memory ability in individuals with aphasia, discussion of how working memory is conceptualised and defined is often missing, as is discussion of results within a theoretical framework. This is critical, as working memory is conceptualised differently across the different theoretical frameworks. They differ in explaining what limits capacity and the source of individual differences as well as how information is encoded, maintained, and retrieved. When test methods are considered within a theoretical framework, specific hypotheses can be tested and stronger conclusions that are less susceptible to different interpretations can be made. Conclusions: Working memory ability has been investigated in numerous studies with individuals with aphasia. To better understand the underlying cognitive constructs that contribute to the language deficits exhibited by individuals with aphasia, future investigations should operationally define the cognitive constructs of interest and discuss findings within theoretical frameworks.

Lexical diversity for adults with and without aphasia across discourse elicitation tasks

Background: Differences in lexical diversity (LD) across different discourse elicitation tasks have been found in neurologically intact adults (NIA) (Fergadiotis, Wright, & Capilouto, 2010) but have not been investigated systematically in people with aphasia (PWA). Measuring lexical diversity in PWA may serve as a useful clinical tool for evaluating the impact of word retrieval difficulties at the discourse level. Aims: The study aims were (a) to explore the differences between the oral language samples of PWA and NIA in terms of LD as measured by dedicated computer software (voc-D), (b) to determine whether PWA are sensitive to discourse elicitation task in terms of LD, and (c) to identify whether differences between PWA and NIA vary in magnitude as a function of discourse task. Method & Procedures: Oral language samples from 25 PWA and 27 NIA were analysed. Participants completed three commonly used discourse elicitation tasks (single pictures, sequential pictures, story telling) and voc-D was used to obtain estimates of their LD. Outcomes & Results: A mixed 2u2009×u20093 ANOVA revealed a significant groupu2009×u2009task interaction that was followed by an investigation of simple main effects and tetrad comparisons. Different patterns of LD were uncovered for each group. For the NIA group results were consistent with previous findings in the literature according to which LD varies as a function of elicitation technique. However, for PWA sequential pictures and story telling elicited comparable estimates of LD. Conclusions: Results indicated that LD is one of the microlinguistic indices that are influenced by elicitation task and the presence of aphasia. These findings have important implications for modelling lexical diversity and selecting and interpreting results from different discourse elicitation tasks.

Automated analysis of the Cinderella story

Background: AphasiaBank is a collaborative project whose goal is to develop an archival database of the discourse of individuals with aphasia. Along with databases on first language acquisition, classroom discourse, second language acquisition, and other topics, it forms a component of the general TalkBank database. It uses tools from the wider system that are further adapted to the particular goal of studying language use in aphasia. Aims: The goal of this paper is to illustrate how TalkBank analytic tools can be applied to AphasiaBank data. Methods &Procedures: Both aphasic (nu2009=u200924) and non-aphasic (nu2009=u200925) participants completed a 1-hour standardised videotaped data elicitation protocol. These sessions were transcribed and tagged automatically for part of speech. One component of the larger protocol was the telling of the Cinderella story. For these narratives we compared lexical diversity across the groups and computed the top 10 nouns and verbs across both groups. We then examined the profiles for two participants in greater detail. Conclusions: Using these tools we showed that, in a story-retelling task, aphasic speakers had a marked reduction in lexical diversity and a greater use of light verbs. For example, aphasic speakers often substituted “girl” for “stepsister” and “go” for “disappear”. These findings illustrate how it is possible to use TalkBank tools to analyse AphasiaBank data.

Productive vocabulary across discourse types.

Aims: The goals of the study were (a) to examine the effect of discourse type on lexical diversity by testing whether there are significant differences among language samples elicited using four discourse tasks (procedures, eventcasts, story telling, and recounts); and (b) to assess the extent to which age influences lexical diversity when different types of discourse are elicited. Methods & Procedures: A total of 86 cognitively healthy adults participated in the study and comprised two groups – young adults (20–29 years old) and older adults (70–89 years old). Participants completed the discourse tasks and their language samples were analysed using dedicated software (voc-D) to obtain estimates of their lexical diversity. Outcomes & Results: A mixed 2u2009×u20094 ANOVA was conducted and followed by an investigation of simple main effects. A lexical diversity hierarchy was established that was similar for both age groups. The study also uncovered age-related differences that were evident when the stimuli were verbally presented but were eliminated when the language samples were elicited using pictorial stimuli. Conclusions: Results indicated that lexical diversity is one of the microlinguistic indices that are influenced by discourse type and age, a finding that carries important methodological implications. Future investigations are warranted to explore the patterns of lexical diversity in individuals with neurogenic language disorders and assess the clinical utility of measures of lexical diversity.

Manipulating task instructions to change narrative discourse performance

Background: A frequent method for eliciting narratives involves presenting picture stimuli and instructing the participant to “tell me what is happening in the picture(s) or tell me everything you see going on in the picture(s)”. It has been suggested that such instructions do not make an explicit request for providing temporal–causal information and so narrative samples frequently comprise listed information. Olness (2006) investigated the effect of task instruction on verb forms produced by adults with aphasia when describing pictures and found that using instructions that explicitly requested temporal–causal information—“Make up your own story about what happened, with a beginning, middle, and an end” (p. 179)—improved the ability of participants to convey the temporal–causal interrelationship depicted in single pictures. Further interpretation of the results was limited due to the lack of non‐brain‐injured participants for comparison. Aims: The purpose of the study was (1) to compare the performance of two groups of healthy older adults on the ability to convey main events in pictured stimuli when different task instructions were provided and (2) to quantify linguistic performance across the two groups and determine if groups significantly differed for any of the linguistic features. Method & Procedures: Participants included 24 healthy older adults assigned to one of two groups based on task instruction: picture description (PD) or storytelling (ST). Instructions were as follows—PD group: “Talk about what is going on in the picture(s)”; ST group: “I want you to look at the picture(s) and tell me a story that has a beginning, middle, and end”. Outcomes & Results: The ST group produced a significantly higher proportion of main events and significantly more past‐tense verbs than the PD group. Two significant relationships among the linguistic measures and main events measure were found for the PD group: a positive relationship between percent of information units (IUs) produced and proportion of main events for the sequential pictures and a negative relationship between D (Malvern & Richards, 1997) and proportion of main events for the single picture stimuli. Conclusions: Findings suggest that task instructions do affect the quality of the narrative produced by healthy older adults. The instructions to provide a story with a beginning, middle, and end may have acted as a scaffold for participants; cueing participants to provide the temporal–causal relationships depicted. Therefore, to better evaluate discourse production abilities in clinical populations, care should be taken in the task instructions provided.

Reliability of main event measurement in the discourse of individuals with aphasia

Background: Quantitative measures of discourse skills of adults with aphasia can be valuable in documenting evidenced‐based practice. Comprehensive assessment of narrative discourse should include a measure of the ability to relay main events (Nicholas & Brookshire, 1995; Wright, Capilouto, Wagovich, Cranfill, & Davis, 2005). Wright et al. (2005) compared the ability of younger and older healthy adults to relate main events in response to pictured stimuli. Results indicated that the younger group produced a significantly higher proportion of main events as compared to the older group and that the main events measure was stable for individual participants over time. However, performance data and data supporting the stability of the main events measure for individuals with aphasia are needed to extend the clinical usefulness of the main events measure as an assessment tool. Aims: The purpose of this study was (a) to compare the performance of healthy adults and adults with aphasia on their ability to convey main events in pictured stimuli and (b) to establish session‐to‐session reliability of the authors main events measure. Methods & Procedures: Eight adults with aphasia (APH) and eight neurologically intact adults (NI) participated in the study. Participants attended two sessions, 7–21 days apart. Each time, participants gave an account of the events from two pictures and two picture sequences (Nicholas & Brookshire, 1993). The resulting language samples were analysed for the proportion of main events conveyed, and test–retest reliability of the measure was assessed. Outcomes & Results: NI adults told a significantly higher proportion of main events than adults with aphasia. The main effect for picture stimulus was also significant; participants told significantly more main events in response to sequential versus single picture stimuli, regardless of group. Test–retest results yielded strong, positive correlations between sessions for both groups. Conclusions: Results indicate that adults with and without aphasia differ in their ability to express the relations and causal links among units of information. Results also indicate that Wright and colleagues (2005) main events measure demonstrates sufficient stability to provide the foundation for its potential use as a pre‐ and post‐treatment measure. Finally, the finding that the proportion of main events provided in response to stimuli varied according to the nature of the stimuli is consistent with the findings of Wright et al. (2005) and suggests that even for individuals with aphasia, relationships between elements depicted in pictures may be more easily identified and conveyed when sequential pictures are provided as stimuli.

Considering a multi-level approach to understanding maintenance of global coherence in adults with aphasia

Background: Discourse is a naturally occurring, dynamic form of communication. Coherence is one aspect of discourse and is a reflection of the listeners ability to interpret the overall meaning conveyed by the speaker. Adults with aphasia may present with impaired maintenance of global coherence, which in turn may contribute to their difficulties in overall communicative competence. Aims: The aim of the study was to determine if microlinguistic processes contribute to maintenance of global coherence in adults with and without aphasia. Method & Procedures: Participants included 15 adults with aphasia (PWA) and 15 healthy controls (HC). Study participants told stories conveyed in wordless picture books. The discourse samples were transcribed and then analysed for percent of information units produced, lexical diversity, syntactic complexity, and maintenance of global coherence. Outcomes & Results: Several linear regression models were carried out to investigate the relationship among the microlinguistic and macrolinguistic measures. For the control group, percent of information units conveyed was a significant predictor of maintenance of global coherence for stories told. For the aphasia group, percent of information units conveyed and lexical diversity were significant predictors of maintenance of global coherence for stories told. Conclusions: Results indicated that microlinguistic processes contribute to the maintenance of global coherence in stories told by adults with aphasia. These findings have important clinical implications for using a multi-level discourse model for analysing discourse ability in adults with aphasia and measuring individual response to treatment.

Using a written cueing hierarchy to improve verbal naming in aphasia

Background: For some individuals with aphasia, writing has been used as an alternative modality for communicating (e.g., Clausen & Beeson, 2003; Lustig & Tompkins, 2002). In some investigations where writing ability was treated; post‐treatment and/or anecdotal reports indicated that verbal naming ability also improved for participants with aphasia (e.g., Beeson, Rising, & Volk, 2003; Kiran, 2005). In some recent studies, investigators have reported that written naming cueing can improve verbal naming ability (DeDe, Parris, & Waters, 2003; Hillis, 1989). This investigation was conducted as a masters thesis by the third author. The authors are especially grateful to the participants for their time and commitment in participating in the study. Aims: The purpose of the present study was to examine the effects of a written cueing treatment programme on verbal naming ability in two adults with aphasia. Method & Procedures: Treatment involved using a written cueing hierarchy, which was modelled after Copy and Recall Treatment (CART; Beeson, 1999) and included verbal and writing components. A modified multiple probe across behaviours design was used to document individual participants response to treatment. The design was replicated across each participant and included baseline, treatment, probe, and maintenance conditions. Outcomes & Results: Both participants improved their verbal naming ability for the target items over the course of treatment, but they responded differently to the treatment. One participant (P2) maintained verbal naming performance for the treated items 4 weeks after treatment ended and generalised to the untrained items; whereas the other participant (P1) did not. Conclusions: Results support and extend previous findings that treating in one modality improves performance in a different modality. Further, participants responded differently to the treatment, suggesting that underlying differences in the participants deficits may account for why they responded differently to the same treatment.