Which of the following is NOT a secondary reinforcer?

CONCEPT: In operant conditioning, reinforcers are classified as PRIMARY or SECONDARY based on how they acquire their reinforcing power. A primary reinforcer satisfies an innate, biological need directly and needs no prior learning (for example food, water, warmth). A secondary (conditioned) reinforcer has no inherent value of its own — it becomes reinforcing only through repeated learned association with a primary reinforcer or with social approval (for example money, grades, tokens, praise).

APPLICATION: Applying this test to the four options: Food directly satisfies hunger, a basic biological need, without any prior learning, so it is a primary reinforcer, not a secondary one. Praise, Grades, and Money, on the other hand, have no biological value by themselves; each becomes rewarding only because a person learns to associate it with approval or with access to primary reinforcers. So among the four, Food is the one that is NOT a secondary reinforcer.

CONTRAST:

• Praise gains its reinforcing value through learned social association with approval and acceptance, so it is a secondary (social) reinforcer, unlike Food.

• Grades gain their reinforcing value because a learner comes to associate them with recognition, opportunity, and future reward, so they are a secondary (symbolic) reinforcer, unlike Food.

• Money has no biological value on its own; it is reinforcing only because it can be exchanged for primary reinforcers, making it the classic secondary (generalized) reinforcer, unlike Food.

RESULT: Hence, the correct answer is Food, the only primary reinforcer among the four options.