Neuroeconomist Paul Zak (author of The Moral Molecule: The Source of Love and Prosperity) has done some work in his lab tracking the measurable effects of story (changing blood chemistry, i.e. levels of oxytocin and cortisol, and areas of brain engagement, using fMRI scans)--the attention, distress, and empathy triggered by same--and mapping them to the classic dramatic arc, first proposed by Gustav Freytag about 150 years ago, of Exposition > Rising Action > Climax > Falling Action > Denouement.
I doubt it will surprise any reader (or viewer) to learn that a good story influences our brain chemistry which in turn influences our behaviour. I've talked about this before: stories work by triggering mirror neurons so that we recreate the experience of others inside ourselves. In other words, story lets us walk in others' shoes without leaving the house and without having to take anyone's shoes away from them.
Empathy is what makes us social animals. Many people believe that its these social propensities that make us human.
What is certain is that story changes us. Story helps make us who we are. Creating story--and sharing the stories others have created--is the most important job of our lives. In a very real sense, story is what makes us who we are.
Watch the video--for experimental purposes I would have tweaked the story of the little boy, sharpened and clarified the arc--but it's instructive:
(via brain pickings, thanks to Karina Sandweg)