Dr. Raheja places a rat in a small cage where it learns to press a bar to obtain a food pellet. Obviously, Dr. Raheja is using a(n) to study learning.

Operant chamber/ Skinner box

Explanation:

Operant chamber also known as Skinner box was developed by B.F skinner in 1930s. Operant chamber are used to study the animal behavior and can be used to both operant and classical conditioning.

In an operant chamber, animal free-operant behaviour is studied through animal response to a stimulus (such as light or voice) and if the reponse was corrrect the animal would be provided with reward.

In the question, Dr. Raheja is using the operant chamber for study learning. The rat would get the food (reward) by pressing a bar (correct response).

thinking it would be physical characteristics

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