The more you spend on others, the happier you feel.
Studies have suggested that losses are, psychologically, twice as powerful as gains. So winning $100 feels as good to us as losing $50 feels bad.
Unexpected Reinforcements Work Best. When rewards are unexpected, there are better chances of a good performance next time.
Some lies are easier to remember than others.
Psychology says the person you care about the most can literally shatter your confidence with their opinions.