I was in it in the 80's and 90's in California. They called it GATE. Gifted And Talented Education. Tons of special testing. I completely forgot about the fast flickering light test until you brought it up. I used to get bussed to another school once per week for the whole day. All the GATE kids in the district would meet once per week at the same school for special classes and tests. There was only maybe 20 of us or so out of 7 or 8 schools.