You do not have any personal connections to the people or animals in the experiment. Also people cannot know if they were given a placebo or not not because of the Placebo effect. The placebo effect is when a person knows they were given a placebo but acts a different way to give the experiment “better” results. You also should eliminate any other pre-existing bias about people you have like a person is nicer if they have a dog. This is called hindsight bias.
