The first painting in which I consciously recorded a photism that I saw during an acupuncture session, called Vision (Fig. 1), was created in 1996.
The idea was that if a photism was an automatic consequence of letter identification, then the photism should interfere with naming the ink colour of these letters on incongruent cards.
Origin
Late 19th century: from Greek phōtismos, from phōtizein 'to shine', from phōs, phōt- 'light'.