There have been many many many studies.
We did one as a class project in college. You can do one in your home if you can get 2 people to help (I think 3 people is as small a group you can have, to have 1 for test group, 1 for control group, and 1 to moderate. With clever design you might bring it down to 2 people.).
Believe me, it has been done to death. Even the KGB and CIA spent cash on it. Look around in the journals if you are really interested.