From the context of the question, I am going to say placebo. This is me assuming, however, that both groups were told that their drinks had the protein powder
Answer:
According to Incentive theories there are two types of motivation - extrinsic and intrinsic. If you are driven by rewards in the form of outside objects like money, you would respond and utilize extrinsic motivation. If you are on the contrary, driven by internal rewards, like experience or joy from the process, you are likely to respond and utilize intrinsic motivation.
Explanation:
