Metaphor Comprehension in Right Brain-Damaged Subjects with Visuo-Verbal and Verbal Material: A Dissociation (Re)Considered

Study of the theory of mind in normal aging: focus on the deception detection and its links with other cognitive functions

Detection of deception is crucial to avoid negative circumstances (financial frauds, social tricks) in daily living. Considering that this cognitive function is especially supported by the prefrontal cortex of the human brain and that these cerebral regions change with advanced age, deception detection may also change with aging. Our purpose is to study this complex ability and its potential links with other cognitive functions, such as the executive control, in normal aging. Thirty-five young adults (YA) aged from 20 to 40, thirty-five old adults (OA) aged from 65 to 79 and thirty very old adults (VOA) aged from 80 to 95 were involved in this study. We propose a novel neuropsychological test (inspired by Theory of Mind Picture Story task) assessing the ability to understand deceptive and cooperative interactions, and tasks involving executive processes (monitoring, task setting, flexibility) to all participants. Between-group analyses show that older participants performed worse than YA on deceptive, cooperative and mixed situations (involving deception and reciprocity) of our task. Significant correlations exist between the deception-cooperation detection and the executive functions. Our results show that these frontal abilities decline after 65 years, even more after 80 years, and they are involved on the deceptive-cooperative situations. The verbal IQ is also linked with the deception-cooperation detection. This suggests that mixed cognitive trainings would allow older adults to detect more easily bad intentions of others, to adjust their behavior to context and to achieve their goals with less risk.

A special role for the right hemisphere in metaphor comprehension?

It has been suggested that the right hemisphere (RH) has a privileged role in the processing of figurative language, including metaphors, idioms, and verbal humor. Previous experiments using hemifield visual presentation combined with human electrophysiology support the idea that the RH plays a special role in joke comprehension. The current study examines metaphoric language. Event-related potentials (ERPs) were recorded as healthy adults read English sentences that ended predictably (High-cloze Literals), or with a plausible but unexpected word (Low-cloze Literals and Low-cloze Metaphoricals). Sentence final words were presented in either the left or the right visual hemifield. Relative to High-cloze Literals, Low-cloze Literals elicited a larger N400 component after presentation to both the left and the right hemifield. Low-cloze Literals also elicited a larger frontal positivity following the N400, but only with presentation to the right hemifield (left hemisphere). These data suggest both cerebral hemispheres can benefit from supportive sentence context, but may suggest an important role for anterior regions of the left hemisphere in the selection of semantic information in the face of competing alternatives. Relative to Low-cloze Literals, Low-cloze Metaphoricals elicited more negative ERPs during the timeframe of the N400 and afterwards. However, ERP metaphoricity effects were very similar across hemifields, suggesting that the integration of metaphoric meanings was similarly taxing for the two hemispheres, contrary to the predictions of the right hemisphere theory of metaphor.

A study of humour and communicative intention following right hemisphere stroke

This research provides further data regarding non-literal language comprehension following right hemisphere damage (RHD). To assess the impact of RHD on the processing of non-literal language, ten participants presenting with RHD and ten matched healthy control participants were administered tasks tapping humour appreciation and pragmatic interpretation of non-literal language. Although the RHD participants exhibited a relatively intact ability to interpret humour from jokes, their use of pragmatic knowledge about interpersonal relationships in discourse was significantly reduced, leading to abnormalities in their understanding of communicative intentions (CI). Results imply that explicitly detailing CI in discourse facilitates RHD participants' comprehension of non-literal language.

Theory of mind—evolution, ontogeny, brain mechanisms and psychopathology

The ability to infer other persons' mental states and emotions has been termed 'theory of mind'. It represents an evolved psychological capacity most highly developed in humans. The evolutionary origins of theory of mind can be traced back in extant non-human primates; theory of mind probably emerged as an adaptive response to increasingly complex primate social interaction. This sophisticated 'metacognitive' ability comes, however, at an evolutionary cost, reflected in a broad spectrum of psychopathological conditions. Extensive research into autistic spectrum disorders has revealed that theory of mind may be selectively impaired, leaving other cognitive faculties intact. Recent studies have shown that observed deficits in theory of mind task performance are part of a broad range of symptoms in schizophrenia, bipolar affective disorder, some forms of dementia, 'psychopathy' and in other psychiatric disorders. This article reviews the evolutionary psychology of theory of mind including its ontogeny and representation in the central nervous system, and studies of theory of mind in psychopathological conditions.

Neural activity associated with metaphor comprehension: spatial analysis

Though neuropsychological data indicate that the right hemisphere (RH) plays a major role in metaphor processing, other studies suggest that, at least during some phases of this processing, a RH advantage may not exist. The present study explores, through a temporally agile neural signal--the event-related potentials (ERPs)--, and through source-localization algorithms applied to ERP recordings, whether the crucial phase of metaphor comprehension presents or not a RH advantage. Participants (n=24) were submitted to a S1-S2 experimental paradigm. S1 consisted of visually presented metaphoric sentences (e.g., "Green lung of the city"), followed by S2, which consisted of words that could (i.e., "Park") or could not (i.e., "Semaphore") be defined by S1. ERPs elicited by S2 were analyzed using temporal principal component analysis (tPCA) and source-localization algorithms. These analyses revealed that metaphorically related S2 words showed significantly higher N400 amplitudes than non-related S2 words. Source-localization algorithms showed differential activity between the two S2 conditions in the right middle/superior temporal areas. These results support the existence of an important RH contribution to (at least) one phase of metaphor processing and, furthermore, implicate the temporal cortex with respect to that contribution.