for about thirty seconds and literally did not see the ad, at all. I am now impressed/scared of my mind's ability to completely disregard probably unimportant information.
Its funny that there is an almost exact same thing in audio processing called masking, where a loud signal will hide a quieter signal similar in frequency.
It's "search satisfaction", I think. People expect to look for (and dismiss) the obvious stuff.
This is similar to the notion that having the TSA check for liquids at airports is dangerous, because when they find a bottle of shampoo, they stop looking for other stuff.
Maybe this is the visual processing equivalent?