Final answer:
Dr. Cheng is practicing cognitive-behavioral therapy (CBT). CBT focuses on changing negative thought patterns and behaviors through various techniques such as shaping, positive reinforcement, negative reinforcement, modeling, and role-playing.
Step-by-step explanation:
Dr. Cheng is practicing cognitive-behavioral therapy (CBT) to help Gary deal with his depression and quit smoking. CBT is a type of therapy that focuses on changing negative thought patterns and behaviors through various techniques.
Shaping is a technique used in CBT to gradually modify behavior by reinforcing small, positive steps towards the desired behavior. Positive reinforcement involves rewarding desired behaviors to encourage their repetition, while negative reinforcement involves removing or avoiding negative stimuli to reinforce the desired behavior.
By using modeling and role-playing, Dr. Cheng is helping Gary learn new ways of thinking and behaving by observing and imitating positive examples. This helps him develop healthier coping strategies and combat negative thought patterns.