Speech graphs and referentiality

In 2023, we published a paper on coreference , in Schizophrenia Bulletin, in collaboration with Alicia Figueroa-Barra and Wolfram Hinzen .

We were inspired by Natalia Mota's work on speech graphs, which represented discourse as a network of words connected by their temporal succession. However our focus was referentiality. We wanted to study how speakers keep track of the different entities they refer to throughout discourse. This was motivated by the idea that referentiality is impaired in schizophrenia, especially when speakers need to maintain and reintroduce the same entities across time.

Example of a referential speech graph
Example of a referential speech graph, where nodes represent entities introduced by noun phrases and edges represent progression through discourse.

In the study, we found that patients with schizophrenia produced a higher density of noun phrases and more recurrences of previously introduced entities. Crucially, these recurrences tended to occur across larger topological distances, suggesting a widening of the temporal window in which entities are maintained and reactivated in discourse.

From this perspective, referential speech graphs are not merely graphs of discourse cohesion; they are approximations of the evolving architecture through which speakers construct and maintain a shared world of reference. In schizophrenia, alterations in these networks may therefore reflect disruptions in the linguistic foundations of thought itself.

You can use the speech graphs renderer to visualize referential speech graphs. The automatic annotation of entities and noun phrases has not yet been developed, but texts can be annotated manually following the proposed scheme.

References:

Mota, N. B., Vasconcelos, N. A. P., Lemos, N., Pieretti, A. C., Kinouchi, O., Cecchi, G. A., Copelli, M., & Ribeiro, S. (2012). Speech graphs provide a quantitative measure of thought disorder in psychosis. PLOS ONE, 7(4), e34928. https://doi.org/10.1371/journal.pone.0034928.

Mota, N. B., Copelli, M., & Ribeiro, S. (2017). Thought disorder measured as random speech structure classifies negative symptoms and schizophrenia diagnosis 6 months in advance. NPJ Schizophrenia, 3, 18. https://doi.org/10.1038/s41537-017-0019-3.

Palominos, C., Figueroa-Barra, A., & Hinzen, W. (2023). Coreference delays in psychotic discourse: widening the temporal window. Schizophrenia Bulletin, 49(Supplement_2), S153–S162. https://doi.org/10.1093/schbul/sbac102.