Cardillo Eileen R, McQuire Marguerite, Chatterjee Anjan
Department of Neurology and Center for Cognitive Neuroscience, University of Pennsylvania, Philadelphia, PA, United States.
Front Psychol. 2018 Dec 3;9:2308. doi: 10.3389/fpsyg.2018.02308. eCollection 2018.
The relative contributions of the left and right hemispheres to the processing of metaphoric language remains unresolved. Neuropsychological studies of brain-injured patients have motivated the hypothesis that the right hemisphere plays a critical role in understanding metaphors. However, the data are inconsistent and the hypothesis is not well-supported by neuroimaging research. To address this ambiguity about the right hemisphere's role, we administered a metaphor sentence comprehension task to 20 left-hemisphere injured patients, 20 right hemisphere injured patients, and 20 healthy controls. Stimuli consisted of metaphors of three different types: predicate metaphors based on action verbs, nominal metaphors based on event nouns, and nominal metaphors based on entity nouns. For each metaphor ( = 60), a closely matched literal sentence with the same source term was also generated. Each sentence was followed by four adjective-noun answer choices (target + three foil types) and participants were instructed to select the phrase that best matched the meaning of the sentence. As a group, both left and right hemisphere patients performed worse on metaphoric than literal sentences, and the degree of this difficulty varied for the different types of metaphor - but there was no difference between the two patient groups. Tests for literal-metaphor dissociations at the level of single cases revealed two types of impairments: general comprehension deficits affecting metaphors and literal sentences equally, and selective metaphor impairments that were specific to different types of metaphor. All cases with selective metaphor deficits had injury to the left hemisphere, and no known comprehension difficulties with literal language. Our results argue against the hypothesis of a specific or necessary contribution of the right hemisphere for understanding metaphoric language. Further, they reveal deficits in metaphoric language comprehension not captured by traditional language assessments, suggesting overlooked communication difficulties in left hemisphere patients.
左、右半球在隐喻性语言处理中的相对作用仍未得到解决。对脑损伤患者的神经心理学研究催生了一种假说，即右半球在理解隐喻中起关键作用。然而，数据并不一致，该假说也未得到神经影像学研究的有力支持。为了解决关于右半球作用的这种模糊性，我们对20名左半球损伤患者、20名右半球损伤患者和20名健康对照者进行了隐喻句理解任务。刺激材料包括三种不同类型的隐喻：基于动作动词的谓语隐喻、基于事件名词的名词隐喻和基于实体名词的名词隐喻。对于每个隐喻（共60个），还生成了一个与之紧密匹配的、带有相同源词的字面句。每个句子后面跟着四个形容词-名词答案选项（目标选项+三种干扰项类型），并指示参与者选择最符合句子意思的短语。总体而言，左、右半球损伤患者在隐喻句上的表现都比字面句差，并且这种困难程度因隐喻类型而异——但两组患者之间没有差异。在单个病例层面上对字面句-隐喻句分离的测试揭示了两种损伤类型：同等影响隐喻句和字面句的一般理解缺陷，以及特定于不同类型隐喻的选择性隐喻损伤。所有有选择性隐喻缺陷的病例都有左半球损伤，且对字面语言没有已知的理解困难。我们的结果反对右半球对理解隐喻性语言有特定或必要贡献的假说。此外，它们揭示了传统语言评估未捕捉到的隐喻性语言理解缺陷，表明左半球患者存在被忽视的沟通困难。
