Why don't we lock them in 8x8x8 rooms with luminescent white walls, floor, and ceiling, of exactly the same brightness. They will never have darkness, never have company, never have anything to hear or read or see, a cup of sugar water a day spiked with amphetamine so they never sleep. The seams of the door and subsistence slot will be so perfectly made that even that will be invisible. A featureless, soundless, empty world, with sound absorbing walls, so they can't even hear their own screams.
Let them shit and piss on the floor and live in it for a week at a time - something at least to bide the time, making snowmen from feces.
Let the shadows of this insane society fall only on them - and then sing songs for the death of children.