I had it to check on why i was having dizzy spells, they thought it was Meneire's Disease 7 years ago. They shoot water into your ear to induce dizzyness. With electrodes attached to your head, the doctors monitor how long it takes for you to recover from the induced dizzyness.
It was torture. If someone did that for how long they wanted, the extreme nausea that is created would be making you cry in less than 5 minutes and begging them to stop. I had to have them stop several times so I could re-adjust to the nausea. Good thing they tell you not to eat breakfast for that morning!
They have all sorts of interesting truth extracting devices.