Yeah, which uses the Placebo Effect.
Stimulants cause reactions of the bodies sensors which in turn cause emotional responces, which stimulate thought and can stimulate reaction.
Thought can resist emotions as well as create new reactions. Thought can be presented as voice or written word.
Voice and written word are stimulates, eyes and ears are sensors.
So as much as a dogs bark can stimulate us to run. So can our own voice and written word can stimulate actions in us.
It has nothing to do with placebo. If the world can effect you, your own words can effect you as well. (IE prayer can effect you).
Besides its a study they have data, you can review the data and make your own opinion. The above is for others that will dimiss actual scientic work because of your words.