A multidisciplinary working group reviewed evidence on the similarities and differences between hallucinations induced by psychedelics and those occurring in schizophrenia-spectrum disorders, examining data from pharmacology, brain imaging, phenomenology, and anthropology. The authors highlight both shared features and distinct characteristics across these scales, and attempt to integrate findings using computational approaches. They conclude with recommendations for future research, emphasizing the need for further study to clarify the relationship between these types of hallucinations.
Intrinsic conscious experiences—thoughts, daydreams, and mind-wandering—make up as much as half of conscious life but are largely ignored in consciousness research because they are methodologically difficult and lack dedicated experimental paradigms. This hypothesis and theory article proposes a new paradigm for studying intrinsic consciousness, modeled on methods used for perceptual consciousness. The authors present exploratory proof-of-concept data, discuss how the paradigm could be used, and address its limitations and possible solutions. They argue that intrinsic consciousness will soon become a standard topic in consciousness studies once suitable experimental tools are developed.
This review addresses two central questions about consciousness: the 'how' (neural correlates and mechanisms) and the 'why' (the hard problem of why conscious experience exists at all). The authors argue that while the hard problem will likely never fully disappear, its significance may diminish as empirical research advances. They predict that future work will be guided by a unifying brain theory—predictive coding—which must explain both perceptual consciousness and conscious mind-wandering to succeed. Such a theory could clarify the function of conscious experience, thereby reducing the weight of the hard problem.