Answer :
The correct answer is shaping.
Shaping refers to a behavioral learning process whereby individuals or animals are gradually taught or trained how to respond to or behave, through reinforcement of responses that are similar or close to the target or desired behavior/ response. In Gary's instance, by rewarding his hamster when it touches a marble with its nose, he is teaching the hamster to gradually roll the marble for a reward.
Shaping refers to a behavioral learning process whereby individuals or animals are gradually taught or trained how to respond to or behave, through reinforcement of responses that are similar or close to the target or desired behavior/ response. In Gary's instance, by rewarding his hamster when it touches a marble with its nose, he is teaching the hamster to gradually roll the marble for a reward.