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Luigi Lombardi

Publications and source records attributed to Luigi Lombardi.

5 recordsLinked to original sources
PubMed2006

Semantic relevance, domain specificity and the sensory/functional theory of category-specificity.

According to the sensory/functional theory of semantic memory, Living items rely more on Sensory knowledge than Non-living ones. The sensory/functional explanation of category-specificity assumes that semantic features are organised on the basis of their content. We report here a study on DAT patients with impaired performance on Living items and tests of Sensory knowledge, and show that this impairment not only disappears after parcelling out semantic relevance, but is also reversed if this parameter is appropriately manipulated. Although semantic relevance model predicts these results [Sartori, G., & Lombardi, L. (2004). Semantic relevance and semantic disorders. Journal of Cognitive Neuroscience, 16, 439-452], they run counter to both the sensory/functional theory and the domain-specific theory of category-specific impairment.

Aged↗
PubMed2005

An ERP study of low and high relevance semantic features.

It is believed that the N400 elicited by concepts belonging to living is larger than N400 to non-living. This is considered as evidence that concepts are organized, in the brain, on the basis of categories. We conducted a feature-verification experiment where living and non-living concepts were matched for relevance of semantic features. Relevance is a measure of the contribution of semantic features to the "core" meaning of a concept. We found that when relevance is low the N400 is large. In addition, we found that when the two categories of living and non-living are equated for relevance the seemingly category effect at behavioral and neural level disappeared. In sum, N400 is sensitive, rather than to categories, to semantic features, thus showing that previously reported effects of semantic categories may arise as a consequence of the differing relevance of concepts belonging to living and non-living categories.

Adult↗
PubMed2005

Feature type effects in semantic memory: an event related potentials study.

It is believed that the N400 elicited by concepts belonging to Living things is larger than the N400 to Non-living things. This is considered as evidence that concepts are organized, in the brain, on the basis of categories. Similarly, differential N400 to Sensory and Non-sensory semantic features is taken as evidence for a neural organisation of conceptual memory based on semantic features. We conducted a feature-verification experiment where Living and Non-living concepts are described by Sensory and Non-sensory features and were matched for Age-of-Acquisition, typicality and familiarity and finally for relevance of semantic features. Relevance is a measure of the contribution of semantic features to the "core" meaning of a concept. We found that when Relevance is low then the N400 is large. In addition, we found that when the two categories of Living and Non-living concepts are matched for relevance the seemingly category effect at the neural level disappeared. Also no difference between Sensory and Non-sensory descriptions was detected when relevance was matched. In sum, N400 does not differ between categories or feature types. Previously reported effects of semantic categories and feature type may have arisen as a consequence of the differing Relevance of concepts belonging to Living and Non-living categories.

Adult↗
PubMed2004

Semantic relevance and semantic disorders.

Semantic features are of different importance in concept representation. The concept elephant may be more easily identified from the feature than from the feature . We propose a new model of semantic memory to measure the relevance of semantic features for a concept and use this model to investigate the controversial issue of category specificity. Category-specific patients have an impairment in one domain of knowledge (e.g., living), whereas the other domain (e.g., nonliving) is relatively spared. We show that categories differ in the level of relevance and that, when concepts belonging to living and nonliving categories are equated to this parameter, the category-specific disorder disappears. Our findings suggest that category specificity, as well as other semantic-related effects, may be explained by a semantic memory model in which concepts are represented by semantic features with associated relevance values.

Adult↗