Psychedelic graphic design has a birthdate: 1966, San Francisco, the Fillmore Auditorium. Concert promoter Bill Graham needed posters for shows by Jefferson Airplane, the Grateful Dead, and a rotating roster of bands attracting increasingly large crowds. The artists he hired — Victor Moscoso, Wes Wilson, Stanley Mouse, Alton Kelley — had no shared style. They invented one.

The design problem was specific: posters needed to be readable from a distance but also interesting up close; they needed to announce events but also function as collectible artifacts; they needed to capture an experience — including the experience of certain altered states — in static print. The solution involved violating every principle of legible typography simultaneously.

Letters bent. Colors vibrated against each other at maximum saturation — the optical effect known as simultaneous contrast, where adjacent complementary colors appear to shift and pulse. Letterforms borrowed from Victorian circus posters, Art Nouveau's organic curves, and the sinuous line work of Aubrey Beardsley, then distorted all of it past recognition. The text became image. The poster was meant to be experienced, not just read.

The style spread globally through the late 1960s, absorbed the visual research of Op Art and psychedelic drug culture, and gave a permanent visual language to an era that has never quite ended.