Flying under the radar: figurative language impairments in focal lesion patients

Abstract

Despite the prevalent and natural use of metaphor in everyday language, the neural basis of this powerful communication device remains poorly understood. Early studies of brain-injured patients suggested the right hemisphere plays a critical role in metaphor comprehension, but more recent patient and neuroimaging studies do not consistently support this hypothesis. One explanation for this discrepancy is the challenge in designing optimal tasks for brain-injured populations. As traditional aphasia assessments do not assess figurative language comprehension, we designed a new metaphor comprehension task to consider whether impaired metaphor processing is missed by standard clinical assessments. Stimuli consisted of 60 pairs of moderately familiar metaphors and closely matched literal sentences. Sentences were presented visually in a randomized order, followed by four adjective-noun answer choices (target + three foil types). Participants were instructed to select the phrase that best matched the meaning of the sentence. We report the performance of three focal lesion patients and a group of 12 healthy, older controls. Controls performed near ceiling in both conditions, with slightly more accurate performance on literal than metaphoric sentences. While the Western Aphasia Battery (Kertesz, 1982) and the objects and actions naming battery (Druks and Masterson, 2000) indicated minimal to no language difficulty, our metaphor comprehension task indicated three different profiles of metaphor comprehension impairment in the patients’ performance. Single case statistics revealed comparable impairment on metaphoric and literal sentences, disproportionately greater impairment on metaphors than literal sentences, and selective impairment on metaphors. We conclude our task reveals that patients can have selective metaphor comprehension deficits. These deficits are not captured by traditional neuropsychological language assessments, suggesting overlooked communication difficulties.

Comprehension of Spatial Metaphors After Right Hemisphere Stroke: A Case Report

“…ZG's metaphor comprehension is also unlike the comprehension pattern of Van Lancker and Kempler's (13) RH-damaged patients, who could not comprehend familiar phrases. Finally, ZG's clinical profile is very similar to the profile of patient 444DX from the Ianni et al (14) study: they both have RH damage, normal language, but compromised memory, executive function and visuo-spatial abilities. Yet, they exhibit different metaphor comprehension patterns: 444DX could not comprehend moderately familiar sentence-level metaphors and literal sentences, which indicates a general sentence level impairment.…”

“…What sets these cases apart is a differential impairment of metaphoric and literal sentence comprehension. Put differently, these patients exhibited three distinct comprehension patterns: the patient with a RH injury had impaired comprehension of both metaphoric and literal sentences at a comparable level; one of the two patients with LH damage had impaired comprehension of both types of sentences, but with significantly more impaired comprehension of metaphors, while the other had impaired comprehension of metaphoric sentences but spared comprehension of literal sentences (14). Taken together, this evidence indicates the existence of a variety of patterns in metaphor comprehension in poststroke patients that goes beyond simple dichotomies, such as novelty vs. familiarity, and involves damage to both cerebral hemispheres.…”

Selective Metaphor Impairments After Left, Not Right, Hemisphere Injury

“…Twenty neurologically healthy older adults recruited from the Center for Cognitive Neuroscience Normal Control Database served as a control population (Age: 63.8 ± 8.7, Education: 14.3 ± 2.5) and were paid $15/h for their participation. All participants were native English speakers, right-handed, and gave informed consent to participate in accordance with the Institutional Review Board of the University of Pennsylvania (data from 12 of these participants was published previously in our related paper; Ianni et al, 2014). Controls did not differ significantly from patients in age or education.…”

“…Third, we chose a task that we have previously demonstrated to be optimized for studying metaphor in focal lesion patients (Ianni et al, 2014). Specifically, we used a metaphor multiple choice task that has the sensitivity to detect metaphor impairments in the absence of traditionally defined aphasia and the specificity to detect impairments of different types of metaphor.…”

Stimulus needs are a moving target: 240 additional matched literal and metaphorical sentences for testing neural hypotheses about metaphor

“…How researchers sample and/or augment the stimuli will depend on their questions of interest, subject populations, and methodology. For example, we recently used SOS to select from both the present items and our previously published set to generate matched sets of nominal-event, nominal-entity, and predicate literal-metaphor pairs, combining them with newly crafted multiple-choice questions to generate a novel assessment of metaphor comprehension in braininjured patients (Ianni, Cardillo, McQuire, & Chatterjee, 2014). The final items were selected such that the metaphor conditions were matched for interpretability, figurativeness, familiarity, naturalness, imageability, length, frequency, and concreteness, and the metaphors and literals were matched for familiarity, length, frequency, concreteness, and valence.…”