The article attempts to evaluate the possible contribution of cognitive psychology to our understanding of Pythia's role in divinatory procedures taking place in the Delphic Oracle. In previous scholarship there was a deep-rooted tendency to search for a natural substance whose digestion should have caused changes in Pythia's mental state. These efforts have recently been revived in the form of a much advertised "Ethylene hypothesis", purportedly harmonizing information of ancient sources with scientific knowledge of modern geology. According to the author of this article, the actual merit of this hypothesis remains very problematic. In contrast, it is argued, based on the evaluation of ancient descriptions of Delphic divinatory consultations and research conducted in the field of cognitive psychology, that Pythia's mental state can be classified as an instance of Patterned Dissociative Identity, which is very often emicly understood as the possession of human mind by spiritual beings. This mental state was adopted by Pythiai routinely and was characterized by stable observable symptoms which warranted the authenticity of spoken oracles in the eyes of consultants and other participants.