Functional MRI of conventional and anomalous metaphors in Mandarin Chinese

This study looks at whether conventional and anomalous metaphors are processed in different locations in the brain while being read when compared with a literal condition in Mandarin Chinese. We find that conventional metaphors differ from the literal condition with a slight amount of increased activation in the right inferior temporal gyrus. In addition, when the anomalous metaphor condition is compared with the literal condition, increased activation occurs bilaterally in the frontal and temporal gyri. Lastly, the comparison between the anomalous and conventional metaphor conditions shows bilateral activation in the middle frontal gyrus and the precentral gyrus, and right-hemisphere activation in the superior frontal gyrus. Left hemisphere activation is found in the inferior frontal gyrus and fusiform gyrus. The left hemisphere activation in the frontal and temporal gyri point to the recruitment of traditional language-based areas for anomalous metaphor sentences, while the right-hemisphere activation found suggests that remote associations are being formed. In short, our study supports the idea that metaphors are not a homogenous type of figurative language and that distinguishing between different types of metaphors will advance theories of language comprehension.     

Right hemisphere metaphor processing? Characterizing the lateralization of semantic processes

Previous laterality studies have implicated the right hemisphere in the processing of metaphors, however it is not clear if this result is due to metaphoricity per se or another aspect of semantic processing. Three divided visual field experiments varied metaphorical and literal sentence familiarity. We found a right hemisphere advantage for unfamiliar sentences containing distant semantic relationships, and a left hemisphere advantage for familiar sentences containing close semantic relationships, regardless of whether sentences were metaphorical or literal. This pattern of results is consistent with theories postulating predominantly left hemisphere processing of close semantic relationships and predominantly right hemisphere processing of distant semantic relationships.     

An fMRI investigation of the neural correlates underlying the processing of novel metaphoric expressions

The neural networks associated with processing related pairs of words forming literal, novel, and conventional metaphorical expressions and unrelated pairs of words were studied in a group of 15 normal adults using fMRI. Subjects read the four types of linguistic expressions and decided which relation exists between the two words (metaphoric, literal, or unrelated). According to the Graded Salience Hypothesis (GSH, ), which predicts a selective RH involvement in the processing of novel, nonsalient meanings, it is primarily the degree of meaning salience of a linguistic expression rather than literality or nonliterality, which modulates the degree of left hemisphere (LH) and right hemisphere (RH) processing of metaphors. In the present study, novel metaphorical expressions represented the nonsalient interpretations, whereas conventional metaphors and literal expressions represented the salient interpretations. A direct comparison of the novel metaphors vs. the conventional metaphors revealed significantly stronger activity in right posterior superior temporal sulcus, right inferior frontal gyrus, and left middle frontal gyrus. These results support the GSH and suggest a special role for the RH in processing novel metaphors. Furthermore, the right PSTS may be selectively involved in verbal creativity.     

The Time-Course of Metaphor Comprehension: An Event-Related Potential Study

ERPs were recorded while subjects were reading short familiar metaphors (e.g., Those fighters are lions), unfamiliar metaphors (Those apprentices are lions), or literal control sentences (Those animals are lions) presented in isolation or preceded by either an irrelevant or relevant context (e.g., They are not idiotic: . . . .” vs. “They are not cowardly: Those fighters are lions”). The terminal word of metaphors elicited larger N400 components than did the terminal word of literal sentences (Experiment 1) suggesting that the (incongruous) literal meaning of metaphors was indeed accessed at some point during comprehension. The analysis of the 600–1000 and 1000–1400 latency bands (Late Positive Components) revealed no significant difference between metaphors and literal sentences. The manipulation of metaphor difficulty (Experiments 2 and 3) also failed to reveal any late effect specifically linked to metaphorical processing. Finally, an effect of the preceding sentence context was found in Experiments 3 and 4, as early as 300 ms following the terminal word onset. Overall, these results support a context-dependent account of metaphor comprehension stating that when contextually relevant, the metaphorical meaning is the only one accessed.     

Enhanced left frontal involvement during novel metaphor comprehension in schizophrenia: Evidence from functional neuroimaging

The neural basis involved in novel metaphor comprehension in schizophrenia is relatively unknown. Fourteen people with schizophrenia and fourteen controls were scanned while they silently read novel metaphors, conventional metaphors, literal expressions, and meaningless word-pairs. People with schizophrenia showed reduced comprehension of both novel and conventional metaphors. Furthermore, while controls showed enhanced brain activation in right inferior frontal gyrus (IFG) for novel metaphors versus meaningless word-pairs, people with schizophrenia showed an over-activation of left IFG and middle frontal gyrus (MFG). Direct comparison between the groups revealed greater activation in left precuneus for both novel metaphors and literal expressions vs. baseline for individuals with schizophrenia. Direct comparison for novel metaphors vs. literal expressions also revealed increased activation for individuals with schizophrenia in left MFG. These results suggest that the inefficient processing of novel metaphors in schizophrenia involves compensatory recruitment of additional brain regions that include the left MFG and left precuneus.     

Functional-anatomical organization of predicate metaphor processing

The bulk of the research on the neural organization of metaphor comprehension has focused on nominal metaphors and the metaphoric relationships between word pairs. By contrast, little work has been conducted on predicate metaphors using verbs of motion such as “The man fell under her spell.” We examined predicate metaphors as compared to literal sentences of motion such as “The child fell under the slide” in an event-related, functional MRI study. Our results demonstrated greater activation in the left inferior frontal cortex and left lateral temporal lobe for predicate metaphors as compared to literal sentences, while no differences were seen in homologous areas of the right hemisphere. We suggest that the results support a neural organization principle for motion processing in which greater abstraction proceeds along a posterior-to-anterior axis within the lateral portion of the left temporal cortex.     

Metaphoric advertisement comprehension: The role of the cerebral hemispheres

Currently little is known about how implicit processes (i.e., cognitive processes that consumers are unaware of) are utilized as consumers read metaphoric advertisements. The field of cognitive neuroscience can help marketers better understand consumers' implicit processing by examining how each cerebral hemisphere uniquely contributes during metaphoric advertisement comprehension. A right hemisphere advantage has been demonstrated during metaphoric language processing; however, it is unclear how each hemisphere of the brain processes metaphors used in advertisements. This study combines the fields of marketing and cognitive neuroscience to investigate the hemispheric processing of metaphoric advertisements. Through the use of the divided visual field paradigm, participants read metaphor, literal, or neutral slogans and responded to related target words presented to either the left visual field‐right hemisphere or the right visual field‐left hemisphere. As predicted, there was a right hemisphere advantage, compared to the left hemisphere, for metaphoric slogans. Additionally, greater facilitation was evident in the right hemisphere for literal slogans compared to metaphoric slogans. Metaphoric messages were also remembered better than literal ones. These findings provide an in‐depth account of how consumers implicitly process messages, suggesting an important role of the right hemisphere during the comprehension of both metaphoric and literal messages. Copyright © 2011 John Wiley & Sons, Ltd.     

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

As the cognitive neuroscience of metaphor has evolved, so too have the theoretical questions of greatest interest. To keep pace with these developments, in the present study we generated a large set of metaphoric and literal sentence pairs ideally suited to addressing the current methodological and conceptual needs of metaphor researchers. In particular, the need has emerged to distinguish metaphors along three dimensions: the grammatical class of their base terms, the sensorimotor features of their base terms, and the syntactic form in which the base terms appear. To meet this need, we generated nominal metaphors (and matched literal sentences) using entity nouns as the base terms, with the intention that they be used in concert with already published sets of predicate metaphors or nominal metaphors using event nouns. Using the results of three norming experiments, we provide 120 pairs of closely matched metaphoric and literal sentences that are characterized along 14 dimensions: 11 at the sentence level (length, frequency, concreteness, familiarity, naturalness, imageability, figurativeness, interpretability, ease of interpretation, valence, and valence judgment reaction time), and three related to the base term (visual, motion, and auditory imagery). These items extend previously published stimuli, filling an extant gap in metaphor research and allowing for tests of new behavioral and neural hypotheses about metaphor.     

Deriving meaning: Distinct neural mechanisms for metaphoric, literal, and non-meaningful sentences

In this study, we used a novel cognitive paradigm and event-related functional magnetic resonance imaging (ER-fMRI) to investigate the neural substrates involved in processing three different types of sentences. Participants read either metaphoric (Some surgeons are butchers), literal (Some surgeons are fathers), or non-meaningful sentences (Some surgeons are shelves) and had to decide whether they made sense or not. We demonstrate that processing of the different sentence types relied on distinct neural mechanisms. Activation of the left inferior frontal gyrus (LIFG), BA 47, was shared by both non-meaningful and metaphoric sentences but not by literal sentences. Furthermore, activation of the left thalamus appeared to be specifically involved in deriving meaning from metaphoric sentences despite lack of reaction times differences between literals and metaphors. We assign this to the ad hoc concept construction and open-endedness of metaphoric interpretation. In contrast to previous studies, our results do not support the view the right hemispheric is specifically involved in metaphor comprehension.     

不同性质的汉语高熟悉度隐喻意义加工过程——来自ERP研究的证据

采用ERP技术考察不同性质隐喻加工的时间进程与神经机制。以词对方式呈现词源性隐喻、引发性隐喻、一般字面义,被试进行语义相关判断任务。结果发现:从引发性隐喻、一般字面义到词源性隐喻,N400平均波幅呈阶梯状递减,引发性隐喻和词源性隐喻的P600平均波幅大于一般字面义。对于不同类型词对诱发的N400,大脑左半球没有显著差异,但右半球上引发性隐喻显著大于词源性隐喻和字面义词对。并且右半球P600平均波幅更大,但三种词对间没有显著差异。结果表明:(1)日常熟悉隐喻的理解更符合平行假说但需要更多的认知资源;(2)右半球是否参与以及参与程度与隐喻性质和加工阶段有关。     

Responses on a lateralized lexical decision task relate to both reading times and comprehension

Research over the last few years has shown that the dominance of the left hemisphere in language processing is less complete than previously thought [Beeman, M. (1993). Semantic processing in the right hemisphere may contribute to drawing inferences from discourse. Brain and Language, 44, 80–120; Faust, M., & Chiarello, C. (1998). Sentence context and lexical ambiguity resolution by the two hemispheres. Neuropsychologia, 36(9), 827–835; Weems, S. A., & Zaidel, E. (2004). The relationship between reading ability and lateralized lexical decision. Brain and Cognition, 55(3), 507–515]. Engaging the right brain in language processing is required for processing speaker/writer intention, particularly in those subtle interpretive processes that help in deciphering humor, irony, and emotional inference. In two experiments employing a divided field or lateralized lexical decision task (LLDT), accuracy and reaction times (RTs) were related to reading times and comprehension on sentence reading. Differences seen in RTs and error rates by visual fields were found to relate to performance. Smaller differences in performance between fields tended to be related to better performance on the LLDT in both experiments and, in Experiment 1, to reading measures. Readers who can exploit both hemispheres for language processing equally appear to be at an advantage in lexical access and possibly also in reading performance.     

Automatic and attentional processes in the comprehension of unfamiliar metaphors

The present study employed priming techniques to investigate whether unfamiliar metaphors are understood automatically, or whether controlled processes are required for comprehension. Priming sentences were presented to 76 participants in a naming task and vocal RT (reaction time) to target words was recorded. Target words were associates of the 120 metaphors used in the stimulus set. SOA (stimulus onset asynchrony) was manipulated in order to permit the measurement of both automatic and attentional priming (375ms, 750ms, and 1,500ms). Four priming conditions enabled a comparison between metaphoric, literal, and neutral contexts, and an unrelated (baseline) condition. The data revealed a strong priming effect for metaphors at an SOA of 1,500ms, but no effects at either of the shorter SOAs. These results indicate that, in the absence of supporting context, unfamiliar metaphors are not processed automatically. Comprehension of such linguistic phenomena apparently requires attentional processing. The findings have implications for direct processing theories of metaphor comprehension.     

Automatic and attentional processes in the comprehension of unfamiliar metaphors

The present study employed priming techniques to investigate whether unfamiliar metaphors are understood automatically, or whether controlled processes are required for comprehension. Priming sentences were presented to 76 participants in a naming task and vocal RT (reaction time) to target words was recorded. Target words were associates of the 120 metaphors used in the stimulus set. SOA (stimulus onset asynchrony) was manipulated in order to permit the measurement of both automatic and attentional priming (375ms, 750ms, and 1,500ms). Four priming conditions enabled a comparison between metaphoric, literal, and neutral contexts, and an unrelated (baseline) condition. The data revealed a strong priming effect for metaphors at an SOA of 1,500ms, but no effects at either of the shorter SOAs. These results indicate that, in the absence of supporting context, unfamiliar metaphors are not processed automatically. Comprehension of such linguistic phenomena apparently requires attentional processing. The findings have implications for direct processing theories of metaphor comprehension.     

The role of working memory in the metaphor interference effect

Participants took longer to judge that metaphors (e.g., an insult is a razor, memory is a warehouse) were literally false than to judge that scrambled sentences (e.g., an insult is a warehouse) were false. This result is the metaphor interference effect (MIE). It demonstrates that metaphor processing is automatic. In this experiment, we found that the magnitude of the MIE is predicted by working memory (WM) capacity, with higher WM yielding a smaller MIE. This suggests that although metaphor comprehension is automatic, the early processing of metaphors is controllable by executive mechanisms. We relate our results to Kintsch’s (2000, 2001) predication model. Specifically, we suggest that mechanisms of WM influence metaphor processing by affecting the effectiveness of the construction-integration process that identifies common properties between topics and vehicles. WM also influences the speed with which meanings are identified as literal or figurative.     

Autumn leaves and old photographs: The development of metaphor preferences

In order to determine the development of preferences for different types of metaphors, a metaphor preferences task was designed. Subjects at seven ages, from 6 through 20 years, received incomplete sentences followed by metaphorical and literal completions, and were asked to select their preferred completions. The pattern of preferences shifted with age. Metaphors based on grounds involving color or shape were preferred by the youngest subjects; metaphors based on movement or sound were preferred by subjects of intermediate age; and metaphors based on nonperceptual, conceptual grounds were preferred by the oldest subjects. At all ages the most frequently chosen metaphors were those based on a combination of two grounds (e.g., color and shape). Preference for literal completions declined with age, but there was an increase in literal selections in the 8th and 10th grades. This study demonstrates the systematic development of aesthetic preferences in the domain of figurative language.     

高功能孤独症者非字面语义理解缺陷：隐喻视角的ERP研究

研究采用事件相关电位技术从隐喻语义理解角度考察了高功能孤独症成人非字面语义理解中的行为特点及脑半球参与模式。行为结果显示：高功能孤独症成人对新异隐喻句的反应时最长,两类隐喻句的反应时均长于普通成人,但错误率上两组被试间无差异。脑电结果显示：高功能孤独症组对新异隐喻句的N400波幅最大,未出现半球偏侧化现象,传统隐喻句在左半球的N400波幅大于右半球,两类隐喻句的N400波幅均大于正常被试。结论：高功能孤独症成人具备隐喻理解能力,并对新异隐喻的理解做出更多努力,但右脑功能异常仍旧存在,左右半球在总体功能或神经联通性上仍旧弱于常人。     

An fMRI investigation of analogical mapping in metaphor comprehension: the influence of context and individual cognitive capacities on processing demands

This study used fMRI to investigate the neural correlates of analogical mapping during metaphor comprehension, with a focus on dynamic configuration of neural networks with changing processing demands and individual abilities. Participants with varying vocabulary sizes and working memory capacities read 3-sentence passages ending in nominal critical utterances of the form "X is a Y." Processing demands were manipulated by varying preceding contexts. Three figurative conditions manipulated difficulty by varying the extent to which preceding contexts mentioned relevant semantic features for relating the vehicle and topic of the critical utterance to one another. In the easy condition, supporting information was mentioned. In the neutral condition, no relevant information was mentioned. In the most difficult condition, opposite features were mentioned, resulting in an ironic interpretation of the critical utterance. A fourth, literal condition included context that supported a literal interpretation of the critical utterance. Activation in lateral and medial frontal regions increased with increasing contextual difficulty. Lower vocabulary readers also had greater activation across conditions in the right inferior frontal gyrus. In addition, volumetric analyses showed increased right temporo-parietal junction and superior medial frontal activation for all figurative conditions over the literal condition. The results from this experiment imply that the cortical regions are dynamically recruited in language comprehension as a function of the processing demands of a task. Individual differences in cognitive capacities were also associated with differences in recruitment and modulation of working memory and executive function regions, highlighting the overlapping computations in metaphor comprehension and general thinking and reasoning.     

科学语言的认知神经加工机制研究:来自ERP的证据

本研究采用尾词范式,使用ERP技术,对比分析了科学语言(隐喻和直义)与日常语言诱发的N400和LPC平均波幅和激活脑区的异同,从而探讨了科学语言认知加工机制的神经特异性。实验结果表明,与日常语言相比,在科学语言认知加工过程中,语义检索和提取难度更大,顶叶区尤其是右顶叶区的激活程度最为显著,左右脑都发挥了重要作用。此外,科学隐喻的相关研究发现支持隐喻加工的意义显性度假说,科学语言特有的复杂性和抽象性降低了语言表达的显性度,并且对后期的语义整合阶段产生影响。     

汉语隐喻理解时程的ERPs研究

摘 要 本研究使用ERPs技术考察隐喻句与本义句理解时程的异同,以研究汉语隐喻的理解机制。以句尾范式向被试随机呈现本义句、熟悉隐喻句、新奇隐喻句及错误义句各50句,被试的任务为判断每句话是否有意义。结果显示：两种隐喻句诱发的N400波形与头皮分布情况和本义句无明显差异,且两种隐喻句诱发的N400波幅高于本义句。本研究结果证明汉语隐喻义和本义理解的认知机制类似,支持隐喻理解的平行加工假说,且加工隐喻义需要耗费更多的认知资源。     

Pure agraphia in Romaji after left inferior frontal gyrus infarction: A case of selective deficit in syllable-to-grapheme conversion in Japanese

The Japanese writing system employs two distinct categories of characters: Kana and Kanji. The difference between Kana and Kanji writing corresponds roughly to that between phonological and lexical systems in Western languages. When typing, most Japanese use alphabetical characters based purely on phonological rules. In particular, the Romaji system is used, in which a syllable consists of a single vowel, a consonant–vowel compound (e.g., ka, ki), or a sequence of consonant–y(semivowel)–vowel (e.g., kya, kyu). We describe a right-handed Japanese patient who developed pure agraphia that affected Romaji writing but preserved Kana and Kanji writing and who had a lesion in the left pars opercularis of the inferior frontal gyrus that extended to the anterior precentral gyrus. The patient demonstrated literal paragraphia in spelling Romaji across modalities. Our findings suggested that the patient’s agraphia in Romaji after a confined left frontal infarction was manifested by a selective impairment in syllable-to-grapheme conversion.