RESUMO
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 #ENTITYSTARTX00026; 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 character's 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 #ENTITYSTARTX00026; 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.
RESUMO
BACKGROUND: For decades researchers assumed visual image generation was the province of the right hemisphere. The lack of corresponding evidence was only recently noted, yet conflicting results still leave open the possibility that the right hemisphere plays a role. This study assessed imagery generation in adult participants with and without right hemisphere damage (RHD). Imagery was operationalised as the activation of representations retrieved from long-term memory similar to those that underlie sensory experience, in the absence of the usual sensory stimulation, and in the presence of communicative stimuli. AIMS: The primary aim of the study was to explore the widely held belief that there is an association between the right hemisphere and imagery generation ability. We also investigated whether visual and visuo-motor imagery generation abilities differ in adults with RHD. METHODS #ENTITYSTARTX00026; PROCEDURES: Participants included 34 adults with unilateral RHD due to cerebrovascular accident and 38 adults who served as non-brain-damaged (NBD) controls. To assess the potential effects of RHD on the processing of language stimuli that differ in imageability, participants performed an auditory sentence verification task. Participants listened to high- and low-imageability sentences from Eddy and Glass (1981) and indicated whether each sentence was true or false. The dependent measures for this task were performance accuracy and response times (RT). OUTCOMES #ENTITYSTARTX00026; RESULTS: In general, accuracy was higher, and response time lower, for low-imagery than for high-imagery items. Although NBD participants' RTs for low-imagery items were significantly faster than those for high-imagery items, this difference disappeared in the group with RHD. We confirmed that this result was not due to a speed-accuracy trade-off or to syntactic differences between stimulus sets. A post hoc analysis also suggested that the group with RHD was selectively impaired in motor, rather than visual, imagery generation. CONCLUSIONS: The disproportionately high RT of participants with RHD in response to low-imagery items suggests that these items had other properties that made their verification difficult for this population. The nature and extent of right hemisphere patients' deficits in processing different types of imagery should be considered. In addition, the capacity of adults with RHD to generate visual and motor imagery should be investigated separately in future studies.
