Reactance: The urge or impulse to maintain and/or restore one’s feeling of freedom.
http://www.youtube.com/watch?v=Kkfx-i31Sbo (See 1:43-2:25)
This clip from Ace Ventura: When Nature Calls represents reactance. Ace Ventura was told not to step on the altar for the Shikaka. This rule was taking away some of Ace Ventura’s freedom. In order to keep some of his feeling of freedom, Ace Ventura impulsively stepped on the altar when the chief was not looking. By defying the chief and showing his freedom, Ace Ventura showed the principle of reactance.