Kimberly M. Meigh

Coarse coding and discourse comprehension in adults with right hemisphere brain damage

Background: Various investigators suggest that some discourse‐level comprehension difficulties in adults with right hemisphere brain damage (RHD) have a lexical‐semantic basis. As words are processed, the intact right hemisphere arouses and sustains activation of a wide‐ranging network of secondary or peripheral meanings and features—a phenomenon dubbed “coarse coding”. Coarse coding impairment has been postulated to underpin some prototypical RHD comprehension deficits, such as difficulties with nonliteral language interpretation, discourse integration, some kinds of inference generation, and recovery when a reinterpretation is needed. To date, however, no studies have addressed the hypothesised link between coarse coding deficit and discourse comprehension in RHD. Aims: The current investigation examined whether coarse coding was related to performance on two measures of narrative comprehension in adults with RHD. Methods & Procedures: Participants were 32 adults with unilateral RHD from cerebrovascular accident, and 38 adults without brain damage. Coarse coding was operationalised as poor activation of peripheral/weakly related semantic features of words. For the coarse coding assessment, participants listened to spoken sentences that ended in a concrete noun. Each sentence was followed by a spoken target phoneme string. Targets were subordinate semantic features of the sentence‐final nouns that were incompatible with their dominant mental representations (e.g., “rotten” for apple). Targets were presented at two post‐noun intervals. A lexical decision task was used to gauge both early activation and maintenance of activation of these weakly related semantic features. One of the narrative tasks assessed comprehension of implied main ideas and details, while the other indexed high‐level inferencing and integration. Both comprehension tasks were presented auditorily. For all tasks, accuracy of performance was the dependent measure. Correlations were computed within the RHD group between both the early and late coarse coding measures and the two discourse measures. Additionally, ANCOVA and independent t‐tests were used to compare both early and sustained coarse coding in subgroups of good and poor RHD comprehenders. Outcomes & Results: The group with RHD was less accurate than the control group on all measures. The finding of coarse coding impairment (difficulty activating/sustaining activation of a words peripheral features) may appear to contradict prior evidence of RHD suppression deficit (prolonged activation for context‐inappropriate meanings of words). However, the sentence contexts in this study were unbiased and thus did not provide an appropriate test of suppression function. Correlations between coarse coding and the discourse measures were small and nonsignificant. There were no differences in coarse coding between RHD comprehension subgroups on the high‐level inferencing task. There was also no distinction in early coarse coding for subgroups based on comprehension of implied main ideas and details. But for these same subgroups, there was a difference in sustained coarse coding. Poorer RHD comprehenders of implied information from discourse were also poorer at maintaining activation for semantically distant features of concrete nouns. Conclusions: This study provides evidence of a variant of the postulated link between coarse coding and discourse comprehension in RHD. Specifically, adults with RHD who were particularly poor at sustaining activation for peripheral semantic features of nouns were also relatively poor comprehenders of implied information from narratives.

A different story on “Theory of Mind” deficit in adults with right hemisphere brain damage

Background: Difficulties in social cognition and interaction can characterise adults with unilateral right hemisphere brain damage (RHD). Some pertinent evidence involves their apparently poor reasoning from a “Theory of Mind” perspective, which requires a capacity to attribute thoughts, beliefs, and intentions in order to understand other peoples behaviour. Theory of Mind is typically assessed with tasks that induce conflicting mental representations. Prior research with a commonly used text task reported that adults with RHD were less accurate in drawing causal inferences about mental states than at making non‐mental‐state causal inferences from control texts. However, the Theory of Mind and control texts differed in the number and nature of competing discourse entity representations. This stimulus discrepancy, together with the explicit measure of causal inferencing, likely put the adults with RHD at a disadvantage on the Theory of Mind texts. This project was supported in part by grant # DC01820 from the National Institute on Deafness and Other Communicative Disorders. The authors are indebted to Denise Balason, Meghan Capellini, Bethany Peters, Anita Lewis, Sara Byers, and Annie Palaika for their assistance. Aims: This study revisited the question of Theory of Mind deficit in adults with RHD. The aforementioned Theory of Mind texts were used but new control texts were written to address stimulus discrepancies, and causal inferencing was assessed relatively implicitly. Adults with RHD were hypothesised not to display a Theory of Mind deficit under these conditions. Methods & Procedures: The participants were 22 adults with unilateral RHD from cerebrovascular accident, and 38 adults without brain damage. Participants listened to spoken texts that targeted either mental‐state or non‐mental‐state causal inferences. Each text was followed by spoken True/False probe sentences, to gauge target inference comprehension. Both accuracy and RT data were recorded. Data were analysed with mixed, two‐way Analyses of Variance (Group by Text Type). Outcomes & Results: There was a main effect of Text Type in both accuracy and RT analyses, with a performance advantage for the Theory of Mind/mental‐state inference stimuli. The control group was faster at responding, and primed more for the target inferences, than the RHD group. The overall advantage for Theory of Mind texts was traceable to one highly conventional inference: someone tells a white lie to be polite. Particularly poor performance in mental‐state causal inferencing was not related to neglect or lesion site for the group with RHD. Conclusions: With appropriate stimulus controls and a relatively implicit measure of causal inferencing, this study found no “Theory of Mind” deficit for adults with RHD. The utility of the “Theory of Mind” construct is questioned. A better understanding of the social communication difficulties of adults with RHD will enhance clinical management in the future.

Activation and maintenance of peripheral semantic features of unambiguous words after right hemisphere brain damage in adults

Background: The right cerebral hemisphere (RH) sustains activation of subordinate, secondary, less common, and/or distantly related meanings of words. Much of the pertinent data come from studies of homonyms, but some evidence also suggests that the RH has a unique maintenance function in relation to unambiguous nouns. In a divided visual field priming study, Atchley, Burgess, and Keeney (1999) reported that only left visual field/RH presentation yielded evidence of continuing activation of peripheral semantic features that were incompatible with the most common image or representation of their corresponding nouns (e.g., rotten for “apple”). Activation for weakly related features that were compatible with the dominant representation (e.g., crunchy) was sustained over time regardless of the visual field/hemisphere of initial stimulus input. Several studies report that unilateral right hemisphere brain damage (RHD) in adults affects the RHs meaning maintenance function, but this work also has centred on homonyms, and/or more recently metonymic and metaphoric polysemous words. Aims: The current investigation examined whether RHD deficits in processing secondary and/or distantly related meanings of words, typically observed in studies of homonyms, would extend to peripheral, weakly related semantic features of unambiguous nouns. Methods & Procedures: Participants were 28 adults with unilateral RHD from cerebrovascular accident, and 38 adults without brain damage. Participants listened to spoken sentences that ended with an unambiguous noun. Each sentence was followed by a spoken target phoneme string. Targets included peripheral semantic features of the sentence‐final noun that were either compatible or incompatible with the dominant mental images of the noun, and were presented at two intervals after that noun. A lexical decision task was used to gauge both the early activation and maintenance of activation for these weakly related semantic features. Outcomes & Results: Accuracy data demonstrated activation (priming) for both types of peripheral features, in both groups, shortly after presentation of the corresponding noun. Neither group evidenced continuing activation for either type of feature at a longer interval. These results are interpreted as reflecting rapid decay/poor maintenance of activation for distantly related features for both groups. The lack of a biasing context, however, did not provide an appropriate test for previously reported suppression deficits after RHD. Fast decay of activation of compatible semantic features was unexpected for the control group. Adults with RHD were less accurate than the control group at both test intervals for the features that are semantically more distant from their associated nouns (Related‐incompatible features). Accordingly, it is argued that the RHD groups poor maintenance of activation for these features reflects a deficit, rather than normal performance. The interpretation of results from this study is complicated by the lack of RT priming for either type of semantic feature, and for either participant group. Conclusions: The right cerebral hemisphere appears to be necessary for activating semantic features that are particularly distantly related to their corresponding lexical items, and for sustaining activation of these features in the absence of a biasing context. Because lexical processing has been linked with discourse comprehension for adults with RHD, more work in this area should enhance clinical management in the future.

A novel, implicit treatment for language comprehension processes in right hemisphere brain damage: Phase I data

Background: This manuscript reports the initial phase of testing for a novel, “Contextual constraint” treatment, designed to stimulate inefficient language comprehension processes in adults with right hemisphere brain damage (RHD). Two versions of treatment were developed to target two normal comprehension processes that have broad relevance for discourse comprehension and that are often disrupted by RHD: coarse semantic coding and suppression. The development of the treatment was informed by two well-documented strengths of the RHD population. The first is consistently better performance on assessments that are implicit, or nearly so, than on explicit, metalinguistic measures of language and cognitive processing. The second is improved performance when given linguistic context that moderately-to-strongly biases an intended meaning. Treatment consisted of providing brief context sentences to prestimulate, or constrain, intended interpretations. Participants made no explicit associations or judgments about the constraint sentences; rather, these contexts served only as implicit primes. Aims: This Phase I treatment study aimed to determine the effects of a novel, implicit, Contextual Constraint treatment in adults with RHD whose coarse coding or suppression processes were inefficient. Treatment was hypothesized to speed coarse coding or suppression function in these individuals. Methods & Procedures: Three adults with RHD participated in this study, one (P1) with a coarse coding deficit and two (P2, P3) with suppression deficits. Probe tasks were adapted from prior studies of coarse coding and suppression in RHD. The dependent measure was the percentage of responses that met predetermined response time criteria. When pre-treatment baseline performance was stable, treatment was initiated. There were two levels of contextual constraint, Strong and Moderate, and treatment for each item began with the provision of the Strong constraint context. Outcomes & Results: Treatment-contingent gains were evident after brief periods of treatment, for P1 on two treatment lists, and for P2. P3 made slower but still substantial gains. Maintenance of gains was evident for P1, the only participant for whom it was measured. Conclusions: This Phase I treatment study documents the potential for considerable gains from an implicit, Contextual constraint treatment. If replicated, this approach to treatment may hold promise for individuals who do poorly with effortful, metalinguistic treatment tasks, or for whom it is desirable to minimize errors during treatment. The real test of this treatments benefit will come from later phase studies of study, which will test broad-based generalization to various aspects of discourse comprehension.

Contextual Constraint Treatment for coarse coding deficit in adults with right hemisphere brain damage: Generalisation to narrative discourse comprehension

Coarse coding is the activation of broad semantic fields that can include multiple word meanings and a variety of features, including those peripheral to a words core meaning. It is a partially domain-general process related to general discourse comprehension and contributes to both literal and non-literal language processing. Adults with damage to the right cerebral hemisphere (RHD) and a coarse coding deficit are particularly slow to activate features of words that are relatively distant or peripheral. This manuscript reports a pre-efficacy study of Contextual Constraint Treatment (CCT), a novel, implicit treatment designed to increase the efficiency of coarse coding with the goal of improving narrative comprehension and other language performance that relies on coarse coding. Participants were four adults with RHD. The study used a single-subject controlled experimental design across subjects and behaviours. The treatment involved pre-stimulation, using a hierarchy of strong and moderately biased contexts, to prime the intended distantly related features of critical stimulus words. Three of the four participants exhibited gains in auditory narrative discourse comprehension, the primary outcome measure. All participants exhibited generalisation to untreated items. No strong generalisation to processing non-literal language was evident. The results indicate that CCT yields both improved efficiency of the coarse coding process and generalisation to narrative comprehension.

Generalization of a Novel, Implicit Treatment for Coarse Coding Deficit in Right Hemisphere Brain Damage: A Single Subject Experiment.

Background: This manuscript reports generalisation effects of Contextual Constraint Treatment for an adult with right hemisphere brain damage (RHD). Contextual Constraint Treatment is designed to stimulate inefficient language comprehension processes implicitly, by providing linguistic context to prime, or constrain, the intended interpretations of treatment stimuli. The study participant had a coarse coding deficit, defined as delayed mental activation of particularly distant semantic features of words (e.g., rotten as a feature of “apple”). Treatment effects were expected to generalise to auditory comprehension of narrative discourse, and perhaps to figurative language interpretation, because coarse coding has been hypothesised and/or demonstrated to support these abilities. Aims: This treatment study aimed to induce generalisation of Contextual Constraint Treatment in an adult with RHD with inefficient coarse coding. Methods & Procedures: The participant in this study was a 75-year-old man with RHD and a coarse coding deficit. A single-participant experimental design across behaviours (stimulus lists) was used to document performance in baseline, treatment, and follow-up phases. Treatment consisted of providing brief, spoken context sentences to prestimulate, or constrain, intended interpretations of stimulus items. The participant made no explicit associations or metalinguistic judgements about the constraint sentences or stimulus words; rather these contexts served only as implicit primes. Probe tasks were adapted from prior work on coarse coding in RHD. The dependent measure was the percentage of responses that met predetermined response time criteria. There were two levels of contextual constraint, Strong and Moderate. Treatment for each item began with the provision of the Strong constraint context, to minimise the production or reinforcement of erroneous or exceedingly slow responses. Generalisation was assessed to a well-standardised measure of narrative discourse comprehension and to several metalinguistic tasks of figurative language interpretation. Outcomes & Results: Treatment-contingent gains, associated with respectable effect sizes, were evident after a brief period of treatment on one stimulus list. Generalisation occurred to untrained items, suggesting that the treatment was facilitating the underlying coarse coding process. Most importantly, generalisation was evident to narrative comprehension performance, for both overall accuracy and accuracy in answering questions about implied information, and all of these gains were maintained through three follow-up sessions. Conclusions: Although the results are still preliminary, this single-participant experimental design documents the potential for meaningful gains from a novel treatment that implicitly targets an underlying language comprehension process in an adult with RHD.

Can high‐level inferencing be predicted by Discourse Comprehension Test performance in adults with right hemisphere brain damage?

Background: Adults with right hemisphere brain damage (RHD) can have considerable difficulty in drawing high‐level inferences from discourse. Standardised tests of language comprehension in RHD do not tap high‐level inferences with many items or in much depth, but nonstandardised tasks lack reliability and validity data. It would be of great clinical value if a standardised test could predict performance on high‐level inferencing measures. Aims: This study addressed whether performance of adults with RHD on the Discourse Comprehension Test (DCT; Brookshire & Nicholas, 1993) could predict their performance on a nonstandardised measure of high‐level inference in narrative comprehension. Methods & Procedures: This study used a within‐group correlational design. Participants were 32 adults with damage limited to the right cerebral hemisphere, as a result of cerebrovascular accident. Half of the participants were male and half female. Participants averaged 64.5 years of age and 14.2 years of education. Participants listened to narrative stimuli and to yes/no questions about each narrative. Each DCT narrative was followed by the standard 8 questions about stated or implied main ideas or details. The high‐level inferencing task contained 6 narrative scenarios from Winner, Brownell, Happé, Blum, and Pincus (1998). Each scenario describes a character who commits a minor transgression and later denies it. Two versions of each story are designed to induce different interpretations of the characters denial. In one version, the character tells a white lie when he is unaware that he was seen committing the transgression. In the other versions, when aware of being seen, the character makes an ironic joke. The narratives were interrupted periodically by comprehension questions. Four Pearson correlation coefficients were computed, between each of two DCT predictor variables (total accuracy for all comprehension questions; accuracy on questions about implied information) and two indicators of high‐level inferencing (total accuracy to answer experimental questions in Joke stories; total accuracy to answer experimental questions in Lie stories). Outcomes & Results: Correlation coefficients were low‐to‐moderate, and nonsignificant. Conclusions: Performance on the DCT by adults with RHD did not predict their high‐level inferencing performance, as measured in this study. The issue that motivated this study should be pursued further in light of the potential advantages to be gained, for both clinical and research purposes. It may be, however, that specific measures of various types of high‐level inferencing will need to be developed and validated.