Hi Ray, you idea is a great one and if fMRI studies were not so expensive I am sure that someone would have done that important study. It costs about $2,000 to run one subject for an hour and much of that time is setup and calibration. With kids it is worse because they have to stay still for the fMRI to get anything usable. As for the 10% figure, that is a myth. If you go to mindsonline.com you can see some fMRI scans synced in time with a video like the Avatar trailer. What you see is the activation of many areas of the brain continuously and it is clear that the brain is highly active during certain areas of the video.

Having said that, I do feel that technology could be used (some day) as a training device to help people know when to "think" certain ways and when not to think those ways. It is the millennial equivalent of biofeedback! Probably will be here sooner than you think!