instinctive drift
the tendency of learned, reinforced behavior to gradually return to a more innate behavior. For example, raccoons trained to drop coins into a container will eventually begin to dip the coins into the container, pull them back out, rub them together, and dip them in again. The learned behavior of dropping coins becomes more representative of the innate behavior of food washing. Also called instinctual drift. [proposed in 1961 by U.S. psychologists Keller Breland (1915–1965) and Marian Breland (1920–2001)]