features were intentionally "incorporated" into the text to make a hoax more realistic, as most of the required academic knowledge of these structures did not exist at the time the Voynich manuscript would have been written. In 2021, researchers at Yale University, using the tf–idf analysis, further investigated the relation between clusters of subjects in the text and topics as they could be identified by illustrations and paleography analysis. Their conclusion is that clusters derived by computation match with the topics of the illustrations to some degree, thus providing evidence that the Voynich manuscript contains meaningful text. However, other scholars have argued that such sophisticated patterns could also appear in hoaxed documents. In 2016, Gordon Rugg and Gavin Taylor published another article in Cryptologia demonstrating that the grille method could reproduce many larger-scale features of the text. In 2019, Torsten Timm and Andreas Schinner published a paper arguing that the text was produced by a process of "self-citation" in which scribes copied and modified meaningless words from earlier in the text. Using a computer simulation of this process, they demonstrated that it could reproduce many of the statistical characteristics of the Voynich manuscript. In 2022, Yale University researchers Daniel Gaskell and Claire Bowern published the results of an experiment in which human participants intentionally tried to write meaningless text. They found that the resulting text was often highly non-random and exhibited many of the same unusual statistical properties as the Voynich manuscript, supporting the idea that some features of the text could have been produced in a hoax. Glossolalia In their 2004 book, Gerry Kennedy and Rob Churchill suggest the possibility that the Voynich manuscript may be a case of glossolalia (speaking-in-tongues), channelling, or outsider art. If so, the author felt compelled to write large amounts of text in a manner which resembles stream of consciousness, either because of voices heard or because of an urge. This often takes place in an invented language in glossolalia, usually made up of fragments of the author's own language, although invented scripts for this purpose are rare. Kennedy and Churchill use Hildegard von Bingen's works to point out similarities between the Voynich manuscript and the illustrations that she drew when she was suffering from severe bouts of migraine, which can induce a trance-like state prone to glossolalia. Prominent features found in both are abundant "streams of stars", and the repetitive nature of the