Story Value: These are human experiences that can shift in quality from positive to negative or negative to positive from moment to moment. For example happy/sad, wisdom/ stupidity, love/hate, freedom/slavery, innocence/experience, etc. Every scene must turn a Story value or it is not a scene. It must start someplace (happy) and end somewhere else (sad) or there is no movement, no change and the Story stops dead in its tracks.
Polarity Shift: The polarity shift is simply shorthand for the value valence change from +/- or -/+. Remember that change can occur in a scene that moves from good to great or bad to worse too. +/++ and -/– are perfectly valid polarity shifts and are essential to building the thriller’s progressive complications. Choosing when to escalate the complications in your overall Story can make or break it from one that “works” to “doesn’t work.”
Turning Point: the precise beat when the value in the scene shifts from positive to negative or negative to positive etc. Turning points can either happen through action (a bomb blows up) or revelation. (“I’m you’re father, Luke.”)
via Tracking the Scene.