I agree, emotion is one of the deadliest things that an investor can have. Emotion makes you sell at the bottom or buy at the top. Emotion can hinder your ability to make a rational investment decision. You may hold on to an investment that should really be sold or buy an investment that you have no business buying. In the long run emotional investors will likely under perform investors with their emotions in check. Also another very important thing you mention is researching investments and not jumping in blindly. Doing this will help you avoid many mistakes and educate you along the way.