Conventional metaphors in longer passages evoke affective brain response

Conventional metaphorical sentences such as She’s a sweet child have been found to elicit greater amygdala activation than matched literal sentences (e.g., She’s a kind child). In the present fMRI study, this finding is strengthened and extended with naturalistic stimuli involving longer passages and a range of conventional metaphors. In particular, a greater number of activation peaks (four) were found in the bilateral amygdala when passages containing conventional metaphors were read than when their matched literal versions were read (a single peak); while the direct contrast between metaphorical and literal passages did not show significant amygdala activation, parametric analysis revealed that BOLD signal changes in the left amygdala correlated with an increase in metaphoricity ratings across all stories. Moreover, while a measure of complexity was positively correlated with an increase in activation of a broad bilateral network mainly involving the temporal lobes, complexity was not predictive of amygdala activity. Thus, the results suggest that amygdala activation is not simply a result of stronger overall activity related to language comprehension, but is more specific to the processing of metaphorical language

Idiomatic expressions evoke stronger emotional responses in the brain than literal sentences

Recent neuroscientific research shows that metaphors engage readers at the emotional level more strongly than literal expressions. What still remains unclear is what makes metaphors more engaging, and whether this generalises to all figurative expressions, no matter how conventionalised they are. This fMRI study aimed to investigate whether idiomatic expressions - the least creative part of figurative language - indeed trigger a higher affective resonance than literal expressions, and to explore possible interactions between activation in emotion-relevant neural structures and regions associated with figurative language processing. Participants silently read for comprehension a set of emotionally positive, negative and neutral idioms embedded in short sentences, and similarly valenced literal sentences. As in studies on metaphors, we found enhanced activation of the left inferior frontal gyrus and left amygdala in response to idioms, indexing stronger recruitment of executive control functions and enhanced emotional engagement, respectively. This suggests that the comprehension of even highly conventionalised and familiar figurative expressions, namely idioms, recruits regions involved in emotional processing. Furthermore, increased activation of the IFG interacted positively with activation in the amygdala, suggesting that the stronger cognitive engagement driven by idioms may in turn be coupled with stronger involvement at the emotional level

Metaphorical sentences are more emotionally engaging than their literal counterparts

Why do people so often use metaphorical expressions when literal paraphrases are readily available? This study focuses on a comparison of metaphorical statements involving the source domain of taste (e.g., She looked at him sweetly) and their literal paraphrases (e.g., She looked at him kindly). Metaphorical and literal sentences differed only in one word and were normed for length, familiarity, imageability, emotional valence, and arousal. Our findings indicate that conventional metaphorical expressions are more emotionally evocative than literal expressions, as the amygdala and the anterior portion of the hippocampus were more active in the metaphorical sentences. They also support the idea that even conventional metaphors can be grounded in sensorimotor and perceptual representations in that primary and secondary gustatory areas (lateral OFC, frontal operculum, anterior insula) were more active as well. A comparison of the individual words that distinguished the metaphorical and literal sentences revealed greater activation in the lateral OFC and the frontal operculum for the taste-related words, supporting the claim that these areas are relevant to taste

Affective and psycholinguistic norms for German conceptual metaphors (COMETA)

Figurative expressions have been shown to play a special role in evoking affective responses, as compared to their literal counterparts. This study provides the first database of conceptual metaphors that includes ratings of affective properties beyond psycholinguistic properties. To allow for the investigation of natural reading processes, 64 natural stories were created, half of which contained two or three conceptual metaphors that relied on the same mapping, whereas the other half contained the metaphors’ literal counterparts. To allow for tighter control and manipulation of the different properties, 120 isolated sentences were also created, half of which contained one metaphorical word, which was replaced by its literal rendering in the other half. All stimuli were rated for emotional valence, arousal, imageability, and metaphoricity, and the pairs of metaphorical and literal stimuli were rated for their similarity in meaning. A measure of complexity was determined and computed. The stories were also rated for naturalness and understandability, and the sentences for familiarity. Differences between the metaphorical and literal stimuli and relationships between the affective and psycholinguistic variables were explored and are discussed in light of extant empirical research. In a nutshell, the metaphorical stimuli were rated as being higher in emotional arousal and easier to imagine than their literal counterparts, thus confirming a role of metaphor in evoking emotion and in activating sensorimotor representations. Affective variables showed the typical U-shaped relationship consistently found in word databases, whereby increasingly positive and negative valence is associated with higher arousal. Finally, interesting differences between the stories and sentences were observed

Metaphorical language processing and amygdala activation in L1 and L2

The present study aims to investigate the neural correlates of processing conventional figurative language in non-native speakers in a comparison with native speakers. Italian proficient L2 learners of German and German native speakers read conventional metaphorical statements as well as literal paraphrases that were comparable on a range of psycholinguistic variables. Results confirm previous findings that native speakers show increased activity for metaphorical processing, and left amygdala activation increases with increasing Metaphoricity. At the whole-brain level, L2 learners showed the expected overall differences in activation when compared to native speakers (in the fronto-temporal network). But L2 speakers did not show any distinctive activation outside the caudate nucleus as Metaphoricity increased, suggesting that the L2 speakers were less affected by increasing Metaphoricity than native speakers were. With small volume correction, only a single peak in the amygdala reached threshold for L2 speakers as Metaphoricity increased. The findings are consistent with the view that metaphorical language is more engaging for native speakers but not necessarily for L2 speakers

Psycholinguistic and affective norms for 1,252 Spanish idiomatic expressions

This study provides psycholinguistic and affective norms for 1,252 Spanish idiomatic expressions. A total of 965 Spanish native speakers rated the idioms in 7 subjective variables: familiarity, knowledge of the expression, decomposability, literality, predictability, valence and arousal. Correlational analyses showed that familiarity has a strong positive correlation with knowledge, suggesting that the knowledge of the figurative meaning of an idiom is highly related to its frequency of use. Familiarity has a moderate positive correlation with final word predictability, indicating that the more familiar an idiom is rated, the more predictable it tends to be. Decomposability shows a moderate positive correlation with literality, suggesting that those idioms whose figurative meaning is easier to deduce from their constituents tend to have a plausible literal meaning. In affective terms, Spanish idioms tend to convey more negative (66%) than positive meanings (33%). Furthermore, valence and arousal show a quadratic relationship, in line with the typical U-shaped relationship found for single words, which means that the more emotionally valenced an idiom is rated, the more arousing it is considered to be. This database will provide researchers with a large pool of stimuli for studying the representation and processing of idioms in healthy and clinical populationsFunders: 1. Spain’s Ministry of Science, Innovation and Universities: https://www.ciencia.gob.es/portal/site/MICINN/ PF: PID2019-107206GB-I00 JAH: RED2018-102615-T, PGC2018-098558-B-I00 2. Rovira i Virgili University: https://www.urv.cat/en/ PF: 2018PFR-URV-B2-32 3. Community of Madrid: https://www.comunidad.madrid JAH: H2019/HUM-5705 4. Galician Department of Education: https://www.edu.xunta.gal/portal/ IF: GRC 2015/006, ED431B 2019/2020S

Conventional metaphors elicit greater real-time engagement than literal paraphrases or concrete sentences

Conventional metaphors (e.g., a firm grasp on an idea) are extremely common. A possible explanation for their ubiquity is that they are more engaging, evoking more focused attention, than their literal paraphrases (e.g., a good understanding of an idea). To evaluate whether, when, and why this may be true, we created a new database of 180 English sentences consisting of conventional metaphors, literal paraphrases, and concrete descriptions (e.g., a firm grip on a doorknob). Extensive norming matched differences across sentence types in complexity, plausibility, emotional valence, intensity, and familiarity of the key phrases. Then, using pupillometry to study the time course of metaphor processing, we predicted that metaphors would elicit greater event-evoked pupil dilation compared to other sentence types. Results confirmed the predicted increase beginning at the onset of the key phrase and lasting seconds beyond the end of the sentence. When metaphorical and literal sentences were compared directly in survey data, participants judged metaphorical sentences to convey “richer meaning,” but not more information. We conclude that conventional metaphors are more engaging than literal paraphrases or concrete sentences in a way that is irreducible to difficulty or ease, amount of information, short-term lexical access, or downstream inferences