An interview with the phenomenologist Steven Lehar

In summer 2025 I had some time to kill on the East Coast in between Vibecamp and The Science of Consciousness Barcelona, so I decided to take the Acela up to Boston for a long overdue meeting with the phenomenologist and vision researcher Steven Lehar.

Lehar has a PhD in Cognitive and Neural Systems from Boston University, where he studied under the well known cognitive scientist Steven Grossberg. He’s also the rational psychonaut’s rational psychonaut – early in his career he discovered that psychedelics such as LSD could be used to deliberately alter subjective experience in a way that he believed was useful for understanding the human vision system and by proxy consciousness. Very briefly, you could say that his core claim is that the brain operates as a harmonic resonator, constructing a fully volumetric world simulation which we navigate from the inside.

Due to the subjective nature of his claims, journals repeatedly rejected his papers – and so he resorted to publishing his ideas on his personal website. He has also published a handful of books, including an autobiographical account of his psychonaut career titled The Grand Illusion (2010). Personally, I think his claims were ahead of their time – it’s just a shame that scientific academia has not yet found a home for his kind of phenomenology. I have found his models of perception to be pretty accurate in the sense that they have formed the foundation of my own view of subjective experience – and I even wrote a three part review of his ideas to help introduce them to a wider audience.

We cover a lot of ground in this interview – Lehar’s early LSD experiences and how they shaped his models of perception; his time at Boston University and the difficulties he had publishing his research; and some very nerdy discussion of psychedelic and dissociative phenomenology. This has been a long time coming; I hope you enjoy it as much as I did.

Websites

• slehar.com
• slehar.wordpress.com
• doubleconformal.wordpress.com
• perceptualoriginsofmath.wordpress.com
• youtube.com/@slehar

Books

• A Cartoon Epistemology (Lehar, 2003)
• The World in Your Head: A Gestalt View of the Mechanism of Conscious Experience (Lehar, 2003)
• The Boundaries of Human Knowledge: A Phenomenological Epistemology (Lehar, 2004)
• The Grand Illusion: A Psychonautical Odyssey Into the Depths of Human Experience (Lehar, 2010)

Papers

• Harmonic Resonance Theory: An Alternative to the “Neuron Doctrine” Paradigm of Neurocomputation to Address Gestalt Properties of Perception (Lehar, 2000)
• The Constructive Aspect of Visual Perception: A Gestalt Field Theory Principle of Visual Reification Suggests a Phase Conjugate Mirror Principle of Perceptual Computation (Lehar, 2008)

Videos

• Nondualita (Lehar, 2016)
• Do We Live in the Real World? (Harvard Science of Psychedelics Club) (Lehar, 2019)
• Harmonic Gestalt: Sound from Structure – A Holistic Invariant Representation of Spatial Structure Through Sound as a Model of Perception (Lehar, 2022)

Blog posts

• Free-Wheeling Hallucinations (Gómez Emilsson, 2019)
• Welcoming Steven Lehar as a QRI Lineage (Gómez Emilsson, 2021)
• An introduction to Steven Lehar, part I: Bubble worlds and force fields (Flipper, 2022)
• An introduction to Steven Lehar, part II: Symmetries and periodicities (Flipper, 2022)
• An introduction to Steven Lehar, part III: Flame fronts and shock scaffolds (Flipper, 2023)

References

• Psychedelics and Mathematical Vision – McKenna, Abraham, Sheldrake Trialogue (Abraham, McKenna & Sheldrake, 1992)
• Brain Mechanisms of Vision (Hubel & Wiesel, 1979)
• Shufflebrain: The Quest for the Hologramic Mind (Pietsch, 1981)
• Nonlinear Optics (Boyd, 2020)
• Traveling Waves Integrate Spatial Information Through Time (Jacobs et al., 2025)
• Human brain networks function in connectome-specific harmonic waves (Atasoy, Donnelly & Pearson, 2016)
• The Devil’s Staircase (Bak, 1986)
• A Primer on the Symmetry Theory of Valence (Johnson, 2023)