I wonder how many of the claims to be able to ignore the flashing is a kind of denial after spending the amount of money required for these devices. I can't imagine how the brain can ignore something so obvious when all reader's attention is narrowly focused on the display screen. Even if it was somehow possible for the brain, the eyes themselves can not be fooled or trained not to react.

If the flashing was to a complete black it might not be as bad as it is. What I find so disturbing, almost hypnotic, is that it displays a negative of the current content. That effect has been used in horror movies to give a very eerie effect. It interrupts the flow of reading not only by its lengthy time but also by disturbing the continuity of the thought process involved in reading.