... [Let's say] pictures of a St. Bernard and a Scottish terrier are flashed before one’s eyes half a second apart, embedded in a series of 20 pictures of cats. In that sequence, most people fail to see the second dog. Their brains have “blinked.”
Scientists explain this blindness as a misallocation of attention. Things are happening too fast for the brain to detect the second stimulus. Consciousness is somehow suppressed.
But the blink is not an inevitable bottleneck, Dr. Davidson said. Most people can identify the second target some of the time. Thus it may be possible to exert some control, which need not be voluntary, over the allocation of attention.
Read Sandra Blakeslee's article describing recent research which shows that meditation "can help train attention".