Happiness is a fundamental object of human existence. To the extent that it is synonymous with pleasure, it could even be said to be one of the “two sovereign masters” that, Jeremy Bentham argued, govern our lives. The other master, lest we forget, is pain. Our happiness is determined by a complex set of voluntary and involuntary factors, ranging from our genes to our health to our wealth. Alas, one determinant of our own happiness that has not received the attention it deserves is the happiness of others. Yet we know that emotions can spread over short periods of time from person to person, in a process known as “emotional contagion.” If someone smiles at you, it is instinctive to smile back. If your partner or roommate is depressed, it is common for you to become depressed.
But might emotions spread more widely than this in social networks—from person to person to person, and beyond? Might an individual's location within a social network influence their future happiness? And might social network processes—by a diverse set of mechanisms—influence happiness not just fleetingly, but also over longer periods of time?