Answer:
Continuous
Fixed ratio
Explanation:
A continuous schedule of reinforcement is a type of reinforcement where the person/animal is reinforced EVERY TIME that he/she provides the expected behavior.
A fixed ratio schedule of reinforcement is a type of reinforcement where the person/animal is reinforced after A FIXED NUMBER of expected behaviors.
The main difference between these two schedules is that one gives a reward every time the behavior takes place, and the other one gives the reward after a fixed number of times.
In this example, Marco initially gives his dog a biscuit EACH TIME he sits on command (therefore, he gives him the biscuit every time the expected behavior takes place).
However, later, he changes the approach and gives the dog a biscuit every fourth time he sits on command (Therefore after a FIXED NUMBER of times the expected behavior takes place.
Thus, Marco has replaced a continuous schedule of reinforcement with a fixed ratio schedule.