Psychedelics and Consciousness: Distinctions, Demarcations, and Opportunities

This review (2021) examines the usage and the meaning of the term ‘consciousness’ within psychedelic research and how theories of consciousness are operationalized to explain the effects of psychedelics in turn. Although psychedelics are unlikely to elucidate the biological basis for phenomenal consciousness (i.e. the hard problem), they are useful tools for investigating claims about the contents of consciousness, and their altered states.


“Psychedelic substances produce unusual and compelling changes in conscious experience which have prompted some to propose that psychedelics may provide unique insights explaining the nature of consciousness. At present, psychedelics, like other current scientific tools and methods, seem unlikely to provide information relevant to the so-called “hard problem of consciousness,” which involves explaining how first-person experience can emerge. However, psychedelics bear on multiple “easy problems of consciousness,” which involve relations between subjectivity, brain function, and behaviour. In this review, we discuss common meanings of the term “consciousness” when used with regard to psychedelics and consider some models of the effects of psychedelics on the brain that have also been associated with explanatory claims about consciousness. We conclude by calling for epistemic humility regarding the potential for psychedelic research to aid in explaining the hard problem of consciousness while pointing to ways in which psychedelics may advance the study of many specific aspects of consciousness.”

Authors: David B. Yaden, Matthew W. Johnson, Roland R. Griffiths, Manoj Doss, Albert Garcia-Romeu, Sandeep Nayak, Natalie Gukasayan, Brian N. Mathur & Frederick S. Barrett


Is your perception of the color red the same as mine? And how does our perception change under the influence of psychedelics? The study of/with psychedelics has given us some preliminary answers as to the content of consciousness. Under ‘altered states of consciousness’ we may experience a red rose with increased intensity, link different concepts, and even link multiple senses (synaesthesia).

What psychedelics don’t (yet) tell us much about is the so-called hard problem of consciousness. Although we can measure the level of changes (as we see in the paper above), we haven’t gained answers as to why we experience anything in the first place.

This paper, by top researchers including David Yaden, Matthew Johnson, and Roland Griffiths, argues that we should be clear and humble when discussing consciousness and psychedelics.

Enlightening quotes from this paper

  • “At present, there is little reason to think that psychedelics will bring us any closer to closing the explanatory gap [between subjective experiences of being and objectively observable phenomena such as brain activity].”
  • “Materialist theories, favored by many scientists, regard phenomenal consciousness as identical to brain states, [but] need to explain how physical processes (e.g., the brain) give rise to qualia,” the “what it feels like” quality of being conscious.”
  • “It is possible that psychedelics will allow altered states of consciousness to follow a similar path of scientific inquiry as emotions by providing a reliable means to induce and influence them in controlled settings.”

The authors argue that psychedelics can play an important role in better understanding the ‘easy problem’ of consciousness. At the same time, they argue that psychedelics currently have not helped elucidate the ‘hard problem’ and don’t see how they could at this time.

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Psychedelics and Consciousness: Distinctions, Demarcations, and Opportunities

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Published in
International Journal of Neuropsychopharmacology
May 14, 2021
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Authors associated with this publication with profiles on Blossom

Manoj Doss
Manoj Doss is a researcher at Johns Hopkins University where he studies the cognitive, emotional, and neural mechanisms of psychedelic drugs.

Roland Griffiths
Roland R. Griffiths is one of the strongest voices in psychedelics research. With over 400 journal articles under his belt and as one of the first researchers in the psychedelics renaissance, he has been a vital part of the research community.

Matthew Johnson
Matthew Johnson is an Associate Professor of Psychiatry and Behavioral Sciences at Johns Hopkins University. His research is concerned with addiction medicine, drug abuse, and drug dependence.

Albert Garcia-Romeu
Albert Garcia-Romeu is one of the principal researchers in the renaissance of psychedelics studies. He is doing his research at Johns Hopkins and focuses on psilocybin and how it can help with treating addiction.

Frederick Barrett
Frederick Streeter Barrett is an Assistant Professor of Psychiatry and Behavioral Sciences and works at the Johns Hopkins University Center for Psychedelic and Consciousness Research.

Natalie Gukasyan
Dr. Natalie Gukasyan is a psychiatrist and post-doctoral research fellow at Johns Hopkins University.


Institutes associated with this publication

Johns Hopkins University
Johns Hopkins University (Medicine) is host to the Center for Psychedelic and Consciousness Research, which is one of the leading research institutes into psychedelics. The center is led by Roland Griffiths and Matthew Johnson.

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