There was an experiment done with children in the 1940's on self regulation. I don't know who did the experiment but it is referenced in a report done on NPR in 2008. Interestingly enough, the experiment was replicated in 2001. Could WATCHTOWER and it's scholarly writers be taking another scientific study out of context and viewing the results through their own 'colored lenses'?
http://www.npr.org/templates/story/story.php?storyId=19212514