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.

One of Steven Lehar’s iconic “bubble world” sketches, from his book A Cartoon Epistemology.

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.

A conversation with Steven Lehar at his home in Massachusetts, about human vision, psychedelic phenomenology, and the world in your head. Video recorded on 2 July 2025.

Steven Lehar demonstrates his bubble world diorama and Kanizsa triangle, which he used to help communicate his theories of human visual perception and the concept of indirect realism. Video recorded on 2 July 2025.

An interview with the phenomenologist Steven Lehar

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