In the almost 70 years since the term was first coined, “outsider art” — a somewhat dismissive designation for the work of self-taught artists — has been steadily finding its way inside the mainstream art world. These days, it is no longer unusual to see pieces by artists with no formal training displayed in even the most prestigious venues; just the past two years have seen such works included in exhibitions mounted by the Venice Biennale, the Museum of Modern Art, the Philadelphia Museum of Art and the Brooklyn Museum, among others.

For much of the past half-century, though, the significance of self-taught art was largely recognized only by a few enthusiasts.