TED Talk: How reliable is your memory?

The legal system heavily relies on eyewitness testimony. The erroneous thinking is that human memory works like a movie: events are committed to an infallible permanent storage system. Instead each time we recall a memory, we recall the memory of an earlier memory. If a detail was missing, then we can fill in information. The danger is that a questioner can lead the witness to plant false information and make people absolutely certain of details that convince a jury but never actually happened. People freed by DNA evidence often were convicted by evidence heavily reliant on eyewitnesses.

Elizabeth Loftus studies false memories.

It might be interesting to control behavior to make people feel disgusted by soda or sugar and enjoy leafy green vegetables. Of course, it is also pretty ethically questionable.