Why is it difficult to test the efficacy of biofeedback using experimental techniques?

Biofeedback involves giving a person real-time information about bodily processes, such as heart rate, so they can learn to control them. To test whether biofeedback itself works, researchers need a control treatment that provides a similar experience without the active feedback; designing that is difficult. The correct choice is “It is difficult to devise a control treatment that replicates biofeedback.”

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