Fred's parents are reinforcing his negative behaviors on a "partial reinforcement schedule".
In partial or intermittent reinforcement, the reaction is reinforced just piece of the time. Learned practices are procured all the more gradually with fractional support, yet the reaction is more impervious to eradication.
While you at first utilized a consistent calendar, strengthening each and every occurrence of the conduct may not generally be practical. In the end, you may choose to change to a fractional calendar where you give support after such a large number of reactions happen or after so much time has passed.