Humanity often pays a high price for progress and understanding — at least, that seems to be the case in many famous psychological experiments. While some famous experiments in psychology have left test subjects temporarily distressed, others have left their participants with life-long psychological issues. In either case, it’s easy to ask the question: “What’s ethical when it comes to science?” Then there are the experiments that involve children, animals, and test subjects who are unaware they’re being experimented on. How far is too far, if the result means a better understanding of the human mind and behavior? We think we’ve found 20 answers to that question with our list of the most unethical experiments in psychology.