Nobel Prize-winning psychologist Daniel Kahneman demonstrated this with his loss aversion theory, showing that people feel the pain of losing money more than they enjoy gains. The natural instinct is to flee the market when it starts to plummet, just as greed prompts people to jump back in when stocks are skyrocketing. Both can have negative impacts. 

But smart investing can overcome the power of emotion by focusing on relevant research, solid data and proven...