Dissociation between syntactic and semantic processing during idiom comprehension

Processes of Emotion Idioms Comprehension of Turkish-Speaking People with Wernicke's Aphasia

INTRODUCTION

Idioms are commonly used in everyday language to convey emotions figuratively. The ability to comprehend and use idioms that incorporate emotional elements is crucial for effective communication in daily life, particularly among people with aphasia (PwA). Despite the interest in understanding the process of emotion idiom comprehension in PwA, limited information is available in the literature. Therefore, this study aimed to investigate the process of emotion idiom comprehension in people with Wernicke's aphasia (PwWA) and compare it with that of neurotypical individuals.

METHODS

Sixty idioms were selected based on their syntactic and semantic features, and participants evaluated their imageability. Sixteen idioms were chosen for the study, and two types of tasks were prepared: written idiom-picture matching and written idiom-written text matching. These tasks were administered to two groups: 11 PwWA and 11 neurotypical individuals. The results were analysed in terms of task performance, response type, syntactic and semantic features, and emotional content.

RESULTS

The emotion idiom comprehension scores of the PwWA group were significantly lower than those of the neurotypical participants. PwWA had greater difficulty with the written idiom-picture matching task and tended to rely on the literal meanings of the idioms. There were differences in the semantic features between the two groups. Among the emotion idioms, PwWA showed significant differences in the types of emotions they were able to comprehend.

CONCLUSIONS

The findings of this study suggest that regardless of the syntactic content of idioms, PwWA's ability to comprehend emotion idioms is impaired, and they tend to interpret them more literally. This study provides a useful method for assessing emotional idiom comprehension in PwA.

The wrong horse was bet on: the effects of argument structure versus argument adjacency on the processing of idiomatic sentences

Introduction

Psycholinguistic research remains puzzled about the circumstances under which syntactically transformed idioms keep their figurative meaning. There is an abundance of linguistic and psycholinguistic studies that have examined which factors may determine why some idioms are more syntactically fixed than others, including transparency, compositionality, and syntactic frozenness; however, they have returned inconclusive, sometimes even conflicting, results. This is the first study to examine argument structure (i.e., the number of arguments a verb takes) and argument adjacency (i.e., the position of the critical arguments relative to the verb) and their effects on the processing of idiomatic and literal sentences in German. Our results suggest that neither the traditional models of idiom processing (according to which idioms are stored as fixed entries) nor more recent hybrid theories (which concede some compositional handling in addition to a fixed entry) adequately account for the effects of argument structure or argument adjacency. Therefore, this study challenges existing models of idiom processing.

Methods

In two sentence-completion experiments, participants listened to idiomatic and literal sentences in both active and passive voice without the sentence-final verb. They indicated which of three visually-presented verbs best completed the sentence. We manipulated the factor argument structure within experiments and argument adjacency across experiments. In Experiment 1, passivized three-argument sentences had the critical argument adjacent to the verb while two-argument sentences had the critical argument non-adjacent to the verb, and vice versa in Experiment 2.

Results

In both experiments, voice interacted with argument structure. Active sentences-both literal and idiomatic-showed equivalent processing of two- and three-argument sentences. However, passive sentences returned contrasting effects. In Experiment 1, three-argument sentences were processed faster than two-argument sentences and vice versa in Experiment 2. This pattern corresponds to faster processing when critical arguments are adjacent than non-adjacent.

Discussion

The results point to the dominant role of argument adjacency over the number of arguments in the processing of syntactically transformed sentences. Regarding idiom processing, we conclude that the adjacency of the verb to its critical arguments determines whether passivized idioms keep their figurative meaning and present the implications of this finding for relevant models of idiom processing.

The neurocognitive basis of Chinese idiomatic constructions and processing differences between native speakers and L2 learners of Mandarin

Classic linguistic analyses assume that syntax is the center of linguistic system. Under this assumption, a finite set of rules can produce an infinite number of sentences. By contrast, construction grammar posits that grammar emerges from language use. Chinese quadrisyllabic idiomatic expressions (QIEs) offer a testing ground for this theoretical construct owing to their high productivity. To understand the cognitive processing of structure and meaning during reading comprehension, we used a semantic judgment task to measure behavioral performance and brain activation (functional MRI). Participants were 19 Mandarin native speakers and 19 L2 learners of intermediate and advanced levels of Mandarin. In the task, participants were instructed to indicate whether the interpretation of a QIE was correct. Our behavioral results showed that L2 learners processed high frequency QIEs faster than low frequency ones. By contrast, low frequency QIEs were processed faster than high frequency ones by native speakers. This phenomenon may be attributed to semantic satiation which impedes the interpretation of high frequency QIEs. To unravel the puzzle, a further functional MRI experiment on native speakers was conducted. The results revealed that the comparison of high-frequency and low-frequency QIEs promoted significant anterior cingulate activation. Also, the comparison of idiomatic and pseudo-idiomatic constructions exhibited significant activation in the bilateral temporal poles, a region that computes semantics rather than syntactic structure. This result indicated that, for native speakers, processing Chinese idiomatic constructions is a conceptually driven process.

Robust Processing Advantage for Binomial Phrases with Variant Conjunctions

Prior research has shown that various types of conventional multiword chunks are processed faster than matched novel strings, but it is unclear whether this processing advantage extends to variant multiword chunks that are less formulaic. To determine whether the processing advantage of multiword chunks accommodates variations in the canonical phrasal template, we examined the robustness of the processing advantage (i.e., Predictability) of binomial phrases with non-canonical conjunctions (e.g., salt and also pepper; salt as well as pepper). Results from the cloze study (Experiment 1) showed that there was a high tendency of producing the canonical conjunct (pepper), even in the binomials that contained non-formulaic conjunctions. Consistent with these findings, results from two eye tracking studies (Experiments 2a and 2b) showed that canonical conjuncts were read faster than novel conjuncts that were matched on word length (e.g., paprika), even in the binomials with variant conjunctions. This robust online processing advantage was replicated in a self-paced reading study that compared all three Conjunction Types (Experiment 3). Taken together, these findings show that binomials with variant function words also receive facilitated processing relative to matched novel strings, even though both types of strings are neither conventional nor relatively frequent. Exploratory analyses revealed that this processing speed advantage was driven by the lexical-semantic association between the canonical conjuncts (salt-pepper), rather than lexical and phrasal frequency. Overall, these results highlight flexibility in the processing of multiword chunks that current models of multiword storage and processing must take into account.

Effects of Structure and Meaning on Cortical Tracking of Linguistic Units in Naturalistic Speech

Recent research has established that cortical activity "tracks" the presentation rate of syntactic phrases in continuous speech, even though phrases are abstract units that do not have direct correlates in the acoustic signal. We investigated whether cortical tracking of phrase structures is modulated by the extent to which these structures compositionally determine meaning. To this end, we recorded electroencephalography (EEG) of 38 native speakers who listened to naturally spoken Dutch stimuli in different conditions, which parametrically modulated the degree to which syntactic structure and lexical semantics determine sentence meaning. Tracking was quantified through mutual information between the EEG data and either the speech envelopes or abstract annotations of syntax, all of which were filtered in the frequency band corresponding to the presentation rate of phrases (1.1-2.1 Hz). Overall, these mutual information analyses showed stronger tracking of phrases in regular sentences than in stimuli whose lexical-syntactic content is reduced, but no consistent differences in tracking between sentences and stimuli that contain a combination of syntactic structure and lexical content. While there were no effects of compositional meaning on the degree of phrase-structure tracking, analyses of event-related potentials elicited by sentence-final words did reveal meaning-induced differences between conditions. Our findings suggest that cortical tracking of structure in sentences indexes the internal generation of this structure, a process that is modulated by the properties of its input, but not by the compositional interpretation of its output.

When the Idiom Advantage Comes Up Short: Eye-Tracking Canonical and Modified Idioms

The literature on idioms often talks about an “idiom advantage,” such that familiar idioms (spill the beans) are generally processed faster than comparable literal phrases (burn the beans). More recently, researchers have explored the processing of idiom modification and while a few studies indicate that familiarity benefits the processing of modified forms, the extent of this facilitation is unknown. In an eye-tracking study, we explored whether familiar idioms and modified versions with 1 or 2 adjectives {spill the [spicy, (red)] beans} are processed faster than matched literal phrases {burn the [spicy, (red)] beans} when both were preceded by a biasing context. The results showed that adjectives inserted in idioms induced longer fixations and were more likely to elicit a regression. However, idiom verbs and final words were processed with the same ease in all adjective conditions, implying that modifying idioms did not impede their processing. In contrast to the widely reported “idiom advantage,” the results demonstrated that canonical and modified idioms were slower to read relative to matched literal controls. This was taken to reflect the competition between an idiom’s literal and figurative meaning, and subsequently the need to select and integrate the contextually appropriate one. In contrast, meaning integration in literal, unambiguous phrases was easier. We argue that processing costs associated with meaning selection may only manifest when idioms are preceded by a biasing context that allows disambiguation to occur in the idiom region, and/or when literal control phrases are contextually appropriate and carefully matched to idioms. Thus, idiom recognition/activation may elicit the well attested idiom advantage, while meaning selection and integration may come at a cost, and idiom modifications may simply add to the cognitive load.

Context and Literality in Idiom Processing: Evidence from Self-Paced Reading

In a self-paced reading study, we investigated how effects of biasing contexts in idiom processing interact with effects of idiom literality. Specifically, we tested if idioms with a high potential for literal interpretation (e.g., break the ice) are processed differently in figuratively and literally biasing contexts than idioms with a low potential (e.g., lose one's cool). Participants read sentences that biased towards a figurative or literal reading of idioms and continued with resolutions that were congruent or incongruent with these biases (e.g., [The new schoolboy/the chilly Eskimo] just wanted to break the ice [with his peers/on the lake]…). While interpretations of high-literality idioms were strengthened by supporting contexts and showed costs for incongruent resolutions, low-literality idioms did not show this effect. Rather, interpreting low-literality idioms in a literal manner showed a cost regardless of context. We conclude that biasing contexts are used in a flexible process of real-time idiom processing and meaning constitution, but this effect is mediated by idiom literality.

Passivizability of Idioms: Has the Wrong Tree Been Barked Up?

A growing number of studies support the partial compositionality of idiomatic phrases, while idioms are thought to vary in their syntactic flexibility. Some idioms, like kick the bucket, have been classified as inflexible and incapable of being passivized without losing their figurative interpretation (i.e., the bucket was kicked ≠ died). Crucially, this has never been substantiated by empirical findings. In the current study, we used eye-tracking to examine whether the passive forms of (flexible and inflexible) idioms retain or lose their figurative meaning. Active and passivized idioms (he kicked the bucket/the bucket was kicked) and incongruous active and passive control phrases (he kicked the apple/the apple was kicked) were inserted in sentences biasing the figurative meaning of the respective idiom (die). Active idioms served as a baseline. We hypothesized that if passivized idioms retain their figurative meaning (the bucket was kicked = died), they should be processed more efficiently than the control phrases, since their figurative meaning would be congruous in the context. If, on the other hand, passivized idioms lose their figurative interpretation (the bucket was kicked = the pail was kicked), then their meaning should be just as incongruous as that of both control phrases, in which case we would expect no difference in their processing. Eye movement patterns demonstrated a processing advantage for passivized idioms (flexible and inflexible) over control phrases, thus indicating that their figurative meaning was not compromised. These findings challenge classifications of idiom flexibility and highlight the creative nature of language.

The syntax-semantics interface in animal vocal communication

Syntax (rules for combining words or elements) and semantics (meaning of expressions) are two pivotal features of human language, and interaction between them allows us to generate a limitless number of meaningful expressions. While both features were traditionally thought to be unique to human language, research over the past four decades has revealed intriguing parallels in animal communication systems. Many birds and mammals produce specific calls with distinct meanings, and some species combine multiple meaningful calls into syntactically ordered sequences. However, it remains largely unclear whether, like phrases or sentences in human language, the meaning of these call sequences depends on both the meanings of the component calls and their syntactic order. Here, leveraging recently demonstrated examples of meaningful call combinations, we introduce a framework for exploring the interaction between syntax and semantics (i.e. the syntax-semantic interface) in animal vocal sequences. We outline methods to test the cognitive mechanisms underlying the production and perception of animal vocal sequences and suggest potential evolutionary scenarios for syntactic communication. We hope that this review will stimulate phenomenological studies on animal vocal sequences as well as experimental studies on the cognitive processes, which promise to provide further insights into the evolution of language. This article is part of the theme issue 'What can animal communication teach us about human language?'

A resting-state study of volumetric and functional connectivity of the habenular nucleus in treatment-resistant depression patients

OBJECTIVE

To investigate the volumetric and functional connectivity of the habenular nucleus in treatment-resistant depression (TRD) patients using the resting-state functional magnetic resonance imaging (rs-fMRI) approach.

METHODS

A total of 15 TRD patients, who visited the Mental Health Institute of the First Hospital Affiliated with Jilin University between August 2014 and March 2015, along with 15 normal subjects, were enrolled into this study for structural and functional imaging. Functional connectivity analysis was performed using bilateral habenular nuclei as the region of interest in contrast to whole-brain voxels.

RESULTS

No significant difference of absolute volume was found in bilateral habenular nuclei between TRD patients and healthy controls, or after controlling for individual total intracranial volume. However, functional connectivity analysis showed increased connectivity between the right habenular nucleus with the medial superior frontal gyrus, anterior cingulate cortex and medial orbitofrontal gyrus, and decreased connectivity with the corpus callosum in the TRD group. For the left habenular nucleus seed, the brain region with increased functional connectivity in the inferior temporal gyrus and decreased functional connectivity in the insular was found in the TRD patients.

CONCLUSION

Abnormal functional connectivity was present between the habenular nucleus and the default mode network in TRD patients. Dysfunction in habenular nucleus-related circuitry for processing negative emotion might form the pathological basis for TRD. Significant asymmetric functional connectivity was also found between bilateral habenular nuclei in TRD patients. Such asymmetry suggests potentially divergent strategy for intervention on bilateral habenular nucleus regions in the future management of depression.

Heart and ____ or Give and ____? An Exploration of Variables That Influence Binomial Completion for Individuals With and Without Aphasia

PURPOSE

The goal of this research was to institute an evidence base behind commonly used elicitation materials known as binomials (e.g., "day and night") that are commonly used for persons with aphasia (PWAs). The study explored a number of linguistic variables that could influence successful binomial completion in nonaphasic adults and PWAs.

METHOD

Thirty nonaphasic adults and 11 PWAs were asked to verbally complete 128 binomials; responses were scored by accuracy and reaction time. Binomials were coded according to the following independent variables: frequency of usage, phonological (e.g., alliteration, rhyme) and semantic (i.e., antonymy) relationships, grammatical category of the response, and number of plausible binomial completions.

RESULTS

Regression analyses demonstrated that, for both groups, greater accuracy was predicted by presence of antonymy and absence of a phonological relationship. Though reaction time models differed between groups, items that elicited a greater number of response options led to longer latencies across participants.

CONCLUSION

Findings suggest that clinicians consider antonymy as well as the number of plausible responses for a given prompt when adapting the level of difficulty for their clients. Results also contribute to broader interdisciplinary research on how automatic language is processed in adults with and without neurogenic communication disorder.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.6030806.

Cognitive and Personality Components Underlying Spoken Idiom Comprehension in Context. An Exploratory Study

In this exploratory study, we investigated whether and to what extent individual differences in cognitive and personality variables are associated with spoken idiom comprehension in context. Language unimpaired participants were enrolled in a cross-modal lexical decision study in which semantically ambiguous Italian idioms (i.e., strings with both a literal and an idiomatic interpretation as, for instance, break the ice), predictable or unpredictable before the string offset, were embedded in idiom-biasing contexts. To explore the contributions of different cognitive and personality components, participants also completed a series of tests respectively assessing general speed, inhibitory control, short-term and working memory, cognitive flexibility, crystallized and fluid intelligence, and personality. Stepwise regression analyses revealed that online idiom comprehension was associated with the participants' working memory, inhibitory control and crystallized verbal intelligence, an association modulated by idiom type. Also personality-related variables (State Anxiety and Openness to Experience) were associated with idiom comprehension, although in marginally significant ways. These results contribute to the renewed interest on how individual variability modulates language comprehension, and for the first time document contributions of individual variability on lexicalized, high frequency multi-word expressions as idioms adding new knowledge to the existing evidence on metaphor and sarcasm.

ERP Evidence for the Activation of Syntactic Structure During Comprehension of Lexical Idiom

The present study used event-related potentials to investigate whether the syntactic structure was activated in the comprehension of lexical idioms, and if so, whether it varied as a function of familiarity and semantic transparency. Participants were asked to passively read the "1+2" structural Chinese lexical idioms with each being presented following 3-5 contextual "1+2" (congruent-structure condition) or "2+1" structural Chinese phrases (incongruent-structure condition). The N400 ERP responses showed more positivity in congruent-structure condition relative to incongruent-structure condition in idioms with high familiarity and high semantic transparency, but less positivity in congruent-structure condition in idioms with high familiarity but low semantic transparency, idioms with low familiarity but high semantic transparency, and idioms with low familiarity and low semantic transparency. Our results suggest that syntactic structure, as the unnecessarity of lexical idiomatic words, was nevertheless activated, independent of familiarity and semantic transparency.

Bilingual and Monolingual Idiom Processing Is Cut from the Same Cloth: The Role of the L1 in Literal and Figurative Meaning Activation

The present study examines non-native (L2) and native (L1) listeners' access to figurative idiomatic meaning and literal constituent meaning in two cross-modal priming experiments. Proficient German learners of English (L2) and native speakers of American English (L1) responded to English target words preceded by English idioms embedded in non-biasing prime sentences in a lexical decision task. English idioms differed in levels of translatability: Lexical level idioms had word-for-word translation equivalents in German, while post-lexical level idioms had matching idiomatic concepts in German but could not be translated word for word. Target words either related to the figurative meaning of the idiom or related to the literal meaning of the final constituent word of the idiom (e.g., to pull someone's leg, literal target: walk, figurative target: joke). Both L1 and L2 listeners showed facilitatory priming for literally- and figuratively-related target words compared to unrelated control target words, with only marginal differences between the listener groups. No effect of translatability was found; that is, the existence of word-for-word translation equivalents in German neither facilitated nor hindered meaning activation for German L2 listeners. The results are interpreted in the context of L1 and L2 models of idiom processing as well as further relevant translation studies.

Sticking your neck out and burying the hatchet: what idioms reveal about embodied simulation

Idioms are used in conventional language twice as frequently as metaphors, but most research, particularly recent work on embodiment has focused on the latter. However, idioms have the potential to significantly deepen our understanding of embodiment because their meanings cannot be derived from their component words. To determine whether sensorimotor states could activate idiomatic meaning, participants were instructed to engage in postures/actions reflecting various idioms (e.g., sticking your neck out) relative to non-idiomatic control postures/actions while reading and responding to statements designed to assess idiomatic meaning. The results showed that statements were generally more strongly endorsed after idiom embodiment than control conditions, indicating that the meaning of idiomatic expressions may not be as disconnected from perceptual and motor experiences than previously thought. These findings are discussed in terms of the mirror neuron system and the necessity of pluralistic contributions from both sensorimotor and amodal linguistic systems to fully account for the representation and processing of idioms and other figurative expressions.

Representing idioms: syntactic and contextual effects on idiom processing

Recent work on the processing of idiomatic expressions argues against the idea that idioms are simply big words. For example, hybrid models of idiom representation, originally investigated in the context of idiom production, propose a priority of literal computation, and a principled relationship between the conceptual meaning of an idiom, its literal lemmas and its syntactic structure. We examined the predictions of the hybrid representation hypothesis in the domain of idiom comprehension. We conducted two experiments to examine the role of syntactic, lexical and contextual factors on the interpretation of idiomatic expressions. Experiment I examines the role of syntactic compatibility and lexical compatibility on the real-time processing of potentially idiomatic strings. Experiment 2 examines the role of contextual information on idiom processing and how context interacts with lexical information during processing. We find evidence that literal computation plays a causal role in the retrieval of idiomatic meaning and that contextual, lexical and structural information influence the processing of idiomatic strings at early stages during processing, which provide support for the hybrid model of idiom representation in the domain of idiom comprehension.

Idiom Comprehension: A Prefrontal Task?

We investigated the neural correlates of idiomatic sentence processing using event-related functional magnetic resonance imaging. Twenty-two healthy subjects were presented with 62 literal sentences and 62 idiomatic sentences, each followed by a picture and were required to judge whether the sentence matched the picture or not. A common network of cortical activity was engaged by both conditions, with the nonliteral task eliciting overall greater activation, both in terms of magnitude and spatial extent. The network that was specifically activated by the nonliteral condition involved the left temporal cortex, the left superior medial frontal gyrus (Brodmann area 9), and the left inferior frontal gyrus (IFG). Activations were also present in the right superior and middle temporal gyri and temporal pole and in the right IFG. In contrast, literal sentences selectively activated the left inferior parietal lobule and the right supramarginal gyrus. An analysis of effective connectivity indicated that the medial prefrontal area significantly increased the connection between frontotemporal areas bilaterally during idiomatic processing. Overall, the present findings indicate a crucial role of the prefrontal cortex in idiom comprehension, which could reflect the selection between alternative sentence meanings.

Testing idiom comprehension in aphasic patients: the effects of task and idiom type

Idiom comprehension in 15 aphasic patients was assessed with three tasks: a sentence-to-picture matching task, a sentence-to-word matching task and an oral definition task. The results of all three tasks showed that the idiom comprehension in aphasic patients was impaired compared to that of the control group, and was significantly affected by the type of task and type of idiom. Whilst performance on the oral definition and sentence-to-picture matching tasks was similarly impaired, the patients performed significantly better on the sentence-to-word matching task. The results confirm the relevance of task and idiom type in drawing conclusions about figurative language interpretation in brain-damaged patients.

Do people use language production to make predictions during comprehension?

We present the case that language comprehension involves making simultaneous predictions at different linguistic levels and that these predictions are generated by the language production system. Recent research suggests that ease of comprehending predictable elements is due to prediction rather than facilitated integration, and that comprehension is accompanied by covert imitation. We argue that comprehenders use prediction and imitation to construct an "emulator", using the production system, and combine predictions with the input dynamically. Such a process helps to explain the rapidity of comprehension and the robust interpretation of ambiguous or noisy input. This framework is in line with a general trend in cognitive science to incorporate action systems into perceptual systems and has broad implications for understanding the links between language production and comprehension.

Is the right hemisphere involved in idiom comprehension? A neuropsychological study

Nonambiguous idiom comprehension was assessed in 15 right brain-damaged (RBD) and 12 left brain-damaged (LBD) aphasic patients by means of a string-to-picture matching task. Idiom comprehension was found to be severely impaired with a bias toward literal interpretation. The RBD patients, though impaired, performed significantly better than LBD patients; their performance was correlated with visuospatial abilities and was significantly affected by lesion site. The results of this study suggest that the performance of RBD patients in the comprehension of idiomatic sentences may be affected by (a) an involvement of the frontal lobe and/or (b) visuospatial deficits that may impair their performance on the picture-matching task.

Left But Not Right Temporal Involvement in Opaque Idiom Comprehension: A Repetitive Transcranial Magnetic Stimulation Study

It has been suggested that figurative language, which includes idioms, is controlled by the right hemisphere. We tested the right hemisphere hypothesis by using repetitive transcranial magnetic stimulation (rTMS) to transiently disrupt the function of the frontal and temporal areas of the right versus left hemisphere in a group of normal participants involved in a task of opaque idiom versus literal sentence comprehension. Forty opaque, nonambiguous idioms were selected. Fifteen young healthy participants underwent rTMS in two sessions. The experiment was run in five blocks, corresponding to the four stimulated scalp positions (left frontal and temporal and right frontal and temporal) and a baseline. Each block consisted of 16 trials—8 trials with idioms and 8 trials with literal sentences. In each trial, the subject was presented with a written sentence, which appeared on the screen for 2000 msec, followed by a pair of pictures for 2500 msec, one of which corresponded to the sentence. The alternative corresponded to the literal meaning for idioms and to a sentence differing in a detail in the case of literal sentences. The subject had to press a button corresponding to the picture matching the string. Reaction times increased following left temporal rTMS, whereas they were unaffected by right hemisphere rTMS, with no difference between idiomatic and literal sentences. Left temporal rTMS also reduced accuracy without differences between the two types of sentences. These data suggest that opaque idiom and literal sentence comprehension depends on the left temporal cortex.

Idiom comprehension in aphasic patients

Idiom comprehension was assessed in 10 aphasic patients with semantic deficits by means of a string-to-picture matching task. Patients were also submitted to an oral explanation of the same idioms, and to a word comprehension task. The stimuli of this last task were the words following the verb in the idioms. Idiom comprehension was severely impaired, with a bias toward the literal interpretation. Very few errors were produced with words, making impossible to establish a correlation between comprehension of idioms and of individual words. The difficulties in idiom comprehension seemed to be due to the fact that patients rely on a literal-first strategy, accessing a figurative interpretation only when the linguistic analysis fails to yield acceptable results.

Idiom comprehension in Alzheimer's disease: the role of the central executive

Idiom comprehension of 15 patients with mild probable Alzheimer's disease was examined by means of a sentence-to-picture matching task. Patients had to choose between two pictures, one representing the figurative and the other the literal interpretation. They were also submitted to a literal sentence comprehension test and to a pencil-and-paper dual task. Whereas literal comprehension was normal in seven subjects and mildly impaired in the others, idiom comprehension was very poor in all of them and correlated with the performance on the dual task. When the idiom test was repeated using an unrelated situation as an alternative to the picture representing the figurative meaning, performance significantly improved. It was hypothesized that the response in the sentence-to-picture matching task in the case of idioms requires sentence processing followed by the suppression of the literal interpretation. Alzheimer's disease patients proved to be unable to inhibit the literal meaning, although they had not lost the idiomatic meaning. In a second experiment, 15 Alzheimer's disease patients with a comparable level of cognitive impairment were submitted to the same idiom comprehension test, and to a test of verbal explanation of the idioms. The results showed significantly better performance in the oral task than in the sentence-to-picture matching task. In oral explanation, however, Alzheimer's disease patients also produced some literal interpretation whenever this represented a possible situation in the real world. We suggest that, during idiom interpretation, the literal meaning needs to be suppressed in order to activate the figurative meaning, and we stress the fact that both linguistic and extralinguistic factors must be taken into account to explain idiom interpretation.