The June issue of the scholarly journal Psychlogical Science has an article titled "Intensive Meditation Training Improves Perceptual Discrimination and Sustained Attention" by Katherine A. MacLean and 12 other people. The article itself is behind a subscription firewall, but the gist of it is that researchers decided Buddhist meditation increases attention span.
Very briefly, the researchers rounded up 60 people and sent 30 to an intensive Buddhist meditation retreat. Tests showed that the meditation group had an enhanced attention span compared to the control group. You can read more about it at Science Daily, next to a stock photo of someone meditating in a position more associated with Hinduism than Buddhism. Baby steps.
Of course, what I want to know is where the intensive retreat was held and what sort of Buddhist meditation they were doing there. No luck with that. I assume it's in the full article, behind the subscription firewall.
At least they've specified "Buddhist" meditation. I get so frustrated with articles about research into meditation that provide no clues what sort of meditation is being discussed. It's a bit like discussing the effects of "exercise" without providing details about the exercise.