Curator, writer, and multimedia artist whose installation pieces included "Performer/Audience/ Mirror" and "Yesterday/Today" both from 1975.
He founded New York's John Daniels Gallery in 1964 at the age of 22. The gallery exhibited the works of minimalist artists such as Sol LeWitt and Carl Andre.
He was once the recipient of the Coutts Contemporary Art Foundation Award.
His father was a chemist and his mother was an educational psychologist.
His work, like that of fellow artist Eva Hesse, adhered to the minimalist aesthetic.