Margaret Lehman Blake

Contextual bias and predictive inferencing in adults with and without right hemisphere brain damage

Background: Impaired inferencing has been suggested to contribute to the comprehension deficits exhibited by adults with right hemisphere brain damage (RHD); however, conflicting results exist concerning the inferencing deficits associated with RHD. Although inference generation has been examined in most of the previous studies, little information is available regarding other processes, such as maintaining inferences over time, the plausibility of inferences in different contexts, and how contextual bias affects these inferencing processes.Aims: The purpose of the study was to examine the influence of contextual bias on the inferencing processes of older adults without brain damage (NBD) and adults with RHD. It was expected that the NBD group would show clear effects of contextual bias. In contrast, the RHD group was expected to use strong contextual bias to guide inferencing, but to have more difficulty in stories that contained weaker contextual bias.Methods & Procedures: A total of 18 older adults without brain damage and 8 individuals with RHD participated in the study. Participants in the RHD group were selected on the basis of a lesion in the right hemisphere, and not the presence of a communication disorder. None evidenced neglect, and as a group they performed similarly to the NBD group on measures of language and working memory. Thinking Out Loud protocols were used to examine the generation, maintenance, and likelihood of predictive inferences, as well as generation of alternative inferences in stories with a low or high probability that a specific outcome would occur. The study was constructed as a mixed design, with group as a between-subjects variable and story condition as a within-subjects variable.Outcomes & Results: Results suggest that contextual bias influenced inference processes in both healthy older adults and individuals with RHD. Both groups used context to qualify the likelihood of inferences, but adults with RHD were less adept at using context to maintain inferences and to restrict inference generation to the most likely outcomes.Conclusions: Adults with RHD who have minimal language deficits can generate predictive inferences and use context to guide some inferencing processes, although they do not use context to constrain inferencing as much as healthy older adults do. The results provide potential insight into the nature of comprehension deficits that may occur after RHD, but the small sample of individuals with minimal cognitive-communication impairments precludes generalisation of the findings to the larger clinical population of adults with RHD.

Characterising comprehension difficulties after right brain damage: Attentional demands of suppression function

Background: Comprehension deficits that typify adults with right brain damage (RBD) have been linked to considerations of processing capacity and processing demands, as well as to ineffective suppression of mental activation that is incompatible with a contextually intended interpretation. Aims: As a first step in investigating how processing resource factors and more specific difficulties like suppression deficits interact to yield characteristic RBD comprehension patterns, the current study was designed to assess whether suppression function consumes attention. Methods & Procedures: A total of 28 RBD and 22 non-brain-damaged adults listened to sentence stimuli that biased the meaning of a sentence-final lexical ambiguity (e.g., “spade”). The suppression task involved speeded judgements of whether a subsequent spoken probe word fitted the overall sentence meaning. In experimental stimuli, the probe word (e.g., “cards”) was unrelated to the biased meaning of the ambiguity. Comparison stimuli ended in an unambiguous word (e.g., “shovel”) that was clearly unrelated to the spoken probe. Thus, slowness after an experimental sentence, relative to its comparison sentence, indicated that the contextually inappropriate meaning of the experimental ambiguity interfered with the probesentence relatedness judgement (i.e., had not been suppressed). In two dual-task conditions, participants allocated 20% or 50% of their “brain power” to a concurrent secondary task, reporting orally whether the probe word consisted of one or two syllables. Outcomes & Results: For both groups, suppression of contextually unintended meanings of lexical ambiguities was more effective in a single-task condition than when attention was shared with a secondary task. The secondary syllable-counting task also suffered when allocated less attention. Conclusions: Effective suppression consumes finite processing capacity. As elaborated in the paper, several combinations of these variables could underlie relatively good and poor comprehension after RBD. Researchers and clinicians need to keep in mind such potential interactions of ineffective comprehension mechanisms, stimulus/task processing demands, and processing capacity.

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.

Influence of Language of Administration on ImPACT Performance by Bilingual Spanish–English College Students

Previous research has suggested that there are performance differences on the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) battery related to language of administration, such that scores are higher with the English than the Spanish version of the battery. This study extended those findings in a within-subjects design, evaluating neurocognitive performance of 58 bilingual English-Spanish-speaking individuals who completed ImPACT in both languages. Results revealed a significant multivariate effect of language of test administration, p < .01; partial η(2) = 0.23, with significantly better English language performance on Verbal Memory and Visual Motor Speed composite scores, but not Visual Memory, Reaction Time, or Total Symptom score. Results are discussed in relation to potential linguistic biases of the ImPACT and functional language dominance that may contribute to the lower scores. These results extend previous findings and suggest a need for separate normative data for Spanish-speaking individuals completing the ImPACT battery if baseline data are not present.

Right-Hemisphere Pragmatic Disorders

Pragmatic deficits are a key component of the communication disorders related to right hemisphere brain damage. The deficits are heterogeneous and include expression and comprehension of prosody, emotion, humor and non-literal language, as well as discourse production and theory of mind. These pragmatic processes are complex and are subserved by extensive neural networks which often include both right and left hemisphere regions. As a result, it is rare to find clear connections between lesion localization and behavior, simple dichotomies of strengths and weaknesses, or consistent patterns of deficits across clients. More research is needed to explore the functional consequences of these deficits and how they can best be treated to improve quality of life for our clients with right hemisphere damage.