Metaphorical and non-metaphorical links: a behavioral and ERP study in young and elderly adults

Comprehension of metaphors in patients with mild cognitive impairment: Evidence from behavioral and ERP data

The ability of metaphor comprehension reflects the cognitive status of elders. This study explored the ability of Chinese aMCI patients to access metaphorical meaning based on linguistic models of metaphor processing. ERPs were recorded from 30 aMCI patients and 30 control participants when judging the meaningfulness of literal sentences, conventional metaphors, novel metaphors, and anomalous expressions. The lower accuracy of the aMCI group revealed an impairment in metaphoric comprehension ability, but this difference was not reflected in ERPs data. In all participants, anomalous endings to sentences evoked the most negative N400 amplitude, whereas conventional metaphors evoked the smallest N400 amplitude. The LPC amplitude might be masked by a metaphor rebound effect when processing novel metaphors, which was consistent with the Graded Salience Model that novel metaphors needed further semantic integration. The results suggest that the aMCI patients may suffer an impairment in metaphorical meaning recognition, which the declined working memory may cause.

Semantic Processing in Healthy Aging and Alzheimer's Disease: A Systematic Review of the N400 Differences

Semantic deficits are common in individuals with Alzheimer’s disease (AD). These deficits notably impact the ability to understand words. In healthy aging, semantic knowledge increases but semantic processing (i.e., the ability to use this knowledge) may be impaired. This systematic review aimed to investigate semantic processing in healthy aging and AD through behavioral responses and the N400 brain event-related potential. The results of the quantitative and qualitative analyses suggested an overall decrease in accuracy and increase in response times in healthy elderly as compared to young adults, as well as in individuals with AD as compared to age-matched controls. The influence of semantic association, as measured by N400 effect amplitudes, appears smaller in healthy aging and even more so in AD patients. Thus, semantic processing differences may occur in both healthy and pathological aging. The establishment of norms of healthy aging for these outcomes that vary between normal and pathological aging could eventually help early detection of AD.

A Test for the Assessment of Pragmatic Abilities and Cognitive Substrates (APACS): Normative Data and Psychometric Properties

The Assessment of Pragmatic Abilities and Cognitive Substrates (APACS) test is a new tool to evaluate pragmatic abilities in clinical populations with acquired communicative deficits, ranging from schizophrenia to neurodegenerative diseases. APACS focuses on two main domains, namely discourse and non-literal language, combining traditional tasks with refined linguistic materials in Italian, in a unified framework inspired by language pragmatics. The test includes six tasks (Interview, Description, Narratives, Figurative Language 1, Humor, Figurative Language 2) and three composite scores (Pragmatic Productions, Pragmatic Comprehension, APACS Total). Psychometric properties and normative data were computed on a sample of 119 healthy participants representative of the general population. The analysis revealed acceptable internal consistency and good test-retest reliability for almost every APACS task, suggesting that items are coherent and performance is consistent over time. Factor analysis supports the validity of the test, revealing two factors possibly related to different facets and substrates of the pragmatic competence. Finally, excellent match between APACS items and scores and the pragmatic constructs measured in the test was evidenced by experts' evaluation of content validity. The performance on APACS showed a general effect of demographic variables, with a negative effect of age and a positive effect of education. The norms were calculated by means of state-of-the-art regression methods. Overall, APACS is a valuable tool for the assessment of pragmatic deficits in verbal communication. The short duration and easiness of administration make the test especially suitable to use in clinical settings. In presenting APACS, we also aim at promoting the inclusion of pragmatics in the assessment practice, as a relevant dimension in defining the patient's cognitive profile, given its vital role for communication and social interaction in daily life. The combined use of APACS with other neuropsychological tests could also improve our understanding of the cognitive substrates of pragmatic abilities and their breakdown.

False memory for idiomatic expressions in younger and older adults: evidence for indirect activation of figurative meanings

Idiomatic expressions can be interpreted literally or figuratively. These two meanings are often processed in parallel or very rapidly, as evidenced by online measures of idiomatic processing. Because in many cases the figurative meaning cannot be derived from the component lexical elements and because of the speed with which this meaning is accessed, it is assumed such meanings are stored in semantic memory. In the present study, we examined how literal equivalents and intact idiomatic expressions are stored in memory and whether episodic memory traces interact or interfere with semantic-level representations and vice versa. To examine age-invariance, younger and older adults studied lists of idioms and literal equivalents. On a recognition test, some studied items were presented in the alternative form (e.g., if the idiom was studied, its literal equivalent was tested). False alarms to these critical items suggested that studying literal equivalents activates the idiom from which they are derived, presumably due to spreading activation in lexical/semantic networks, and results in high rates of errors. Importantly, however, the converse (false alarms to literal equivalents after studying the idiom) were significantly lower, suggesting an advantage in storage for idioms. The results are consistent with idiom processing models that suggest obligatory access to figurative meanings and that this access can also occur indirectly, through literal equivalents.

Norming the odd: creation, norming, and validation of a stimulus set for the study of incongruities across music and language

Research into similarities between music and language processing is currently experiencing a strong renewed interest. Recent methodological advances have led to neuroimaging studies presenting striking similarities between neural patterns associated with the processing of music and language--notably, in the study of participants' responses to elements that are incongruous with their musical or linguistic context. Responding to a call for greater systematicity by leading researchers in the field of music and language psychology, this article describes the creation, selection, and validation of a set of auditory stimuli in which both congruence and resolution were manipulated in equivalent ways across harmony, rhythm, semantics, and syntax. Three conditions were created by changing the contexts preceding and following musical and linguistic incongruities originally used for effect by authors and composers: Stimuli in the incongruous-resolved condition reproduced the original incongruity and resolution into the same context; stimuli in the incongruous-unresolved condition reproduced the incongruity but continued postincongruity with a new context dictated by the incongruity; and stimuli in the congruous condition presented the same element of interest, but the entire context was adapted to match it so that it was no longer incongruous. The manipulations described in this article rendered unrecognizable the original incongruities from which the stimuli were adapted, while maintaining ecological validity. The norming procedure and validation study resulted in a significant increase in perceived oddity from congruous to incongruous-resolved and from incongruous-resolved to incongruous-unresolved in all four components of music and language, making this set of stimuli a theoretically grounded and empirically validated resource for this growing area of research.

Brainwaves are stethoscopes: ERP correlates of novel metaphor comprehension

The processing of unfamiliar metaphors was examined using event related potentials (ERPs). We compared the patterns of brain electrical activity elicited by processing two-word expressions denoting literal, conventional metaphoric, and novel metaphoric meaning, as well as unrelated word pairs. Participants performed a semantic judgment task in which they decided whether each word pair conveyed a meaningful expression. N400 amplitude to the second word of the pair varied as a function of expression type in a graded manner increasing from literal expressions to conventional metaphors, to novel metaphors and to unrelated pairs. N400s elicited by novel metaphors showed a right-biased scalp distribution as compared to those elicited by conventional metaphors. Novel metaphors also elicited a right-sided late negativity suggesting further attempts to integrate meaning in a non-literal fashion, a result that supports the sequential view of novel metaphor comprehension. These findings are consistent with recent brain imaging studies and complement them by adding the temporal dynamics dimension.

Dynamics of hemispheric activity during metaphor comprehension: Electrophysiological measures

Brain imaging studies have lead to conflicting findings regarding the involvement of the right hemisphere (RH) in metaphor comprehension. Some report more relative RH activation when processing figurative expressions but others have shown just the opposite. The inconsistencies might be a result of the low temporal resolution related to current brain imaging techniques which is insufficient to uncover patterns of hemispheric interaction that change over time. Event-related potentials and a source estimation technique (LORETA) were used to investigate such temporal interactions when processing two-word expressions denoting literal, conventional metaphoric, and novel metaphoric meaning, as well as unrelated word pairs. Participants performed a semantic judgment task in which they decided whether each word pair conveyed a meaningful expression. Our findings indicate that during comprehension of novel metaphors there are some stages of considerable RH involvement, mainly of the temporal and superior frontal areas. Although the processing mechanisms used for all types of expressions were similar and require both hemispheres, the relative contribution of each hemisphere at specific processing stages depended on stimulus type. Those stages correspond roughly to the N400 and LPC components which reflect semantic and contextual integration, respectively. The present study demonstrates that RH mechanisms are necessary, but not sufficient, for understanding metaphoric expressions. Both hemispheres work in concert in a complex dynamical pattern during literal and figurative language comprehension. Electrophysiological recordings together with source localization algorithms such as LORETA are a viable tool for measuring this type of activity patterns.

On understanding idiomatic language: The salience hypothesis assessed by ERPs

Giora's [Giora, R., 1997. Understanding figurative and literal language: the Graded Salience Hypothesis. Cogn. Linguist. 7 (1), 183-206; Giora, R., 2003. On Our Mind: Salience Context and Figurative Language. Oxford Univ. Press, New York] Graded Salience Hypothesis states that more salient meanings-coded meanings foremost on our mind due to conventionality, frequency, familiarity, or prototypicality-are accessed faster than and reach sufficient levels of activation before less salient ones. This research addresses predictions derived from this model by examining the salience of familiar and predictable idioms, presented out of context. ERPs recorded from 30 subjects involved in reading and lexical decision tasks to (strongly/weakly) salient idioms and (figurative/literal) targets indicate that N400 amplitude was smaller for the last word of the strongly salient idioms than for the weakly salient idioms. Moreover, N400 amplitude of probes related to the salient meaning of strongly salient idioms was smaller than those of the 3 other conditions. In addition, response times to salient interpretations (the idiomatic meanings of highly salient idioms and the literal interpretations of less salient idioms) were shorter compared to the other conditions. These findings support Giora's Graded Salience Hypothesis. They show that salient meanings are accessed automatically, regardless of figurativity.