The entropic tongue: Disorganization of natural language under LSD

Camila Sanz, Carla Pallavicini, Facundo Carrillo, Federico Zamberlan, Mariano Sigman, Natalia Mota, Mauro Copelli, Sidarta Ribeiro, David Nutt, Robin Carhart-Harris, Enzo Tagliazucchi

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Serotonergic psychedelics have been suggested to mirror certain aspects of psychosis, and, more generally, elicit a state of consciousness underpinned by increased entropy of on-going neural activity. We investigated the hypothesis that language produced under the effects of lysergic acid diethylamide (LSD) should exhibit increased entropy and reduced semantic coherence. Computational analysis of interviews conducted at two different time points after 75 μg of intravenous LSD verified this prediction. Non-semantic analysis of speech organization revealed increased verbosity and a reduced lexicon, changes that are more similar to those observed during manic psychoses than in schizophrenia, which was confirmed by direct comparison with reference samples. Importantly, features related to language organization allowed machine learning classifiers to identify speech under LSD with accuracy comparable to that obtained by examining semantic content. These results constitute a quantitative and objective characterization of disorganized natural speech as a landmark feature of the psychedelic state.

Original languageEnglish
Article number103070
JournalConsciousness and Cognition
StatePublished - Jan 2021
Externally publishedYes


  • Entropy
  • LSD
  • Natural language
  • Psychedelics
  • Psychosis


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