Psychology researchers can be a nosy bunch. For 13 years, a group of psychologists at UC Berkeley led by Dr. Robert Levenson tracked 87 middle-aged and older married couples who had been married for 15 to 35 years to see how their relationships evolved over time.
For the study, researchers observed the married couples in a laboratory setting while the couples talked about their marriages. Here’s the summary from Berkeley’s press release:
The spouses’ listening and speaking behaviors were coded and rated according to their facial expressions, body language, verbal content and tone of voice. Emotions were coded into the categories of anger, contempt, disgust, domineering behavior, defensiveness, fear, tension, sadness, whining, interest, affection, humor, enthusiasm and validation.
Researchers found that both middle-aged and older couples, regardless of their satisfaction with their relationship, experienced increases in overall positive emotional behaviors with age, while experiencing a decrease in overall negative emotional behaviors.
In other words, as time went on, married couples treated each other better. This is good news for long-term marriages.
But there’s a caveat: survivorship bias.
Survivorship bias is a mistake that comes from counting only successes and ignoring failures. The term supposedly originated from a story about the ancient Greek philosopher Diogenes.
Diogenes was a bit of a crank. He was banished from one city for debasing the currency (a form of counterfeiting), begged for a living, and often slept in a large ceramic jar. Diogenes preached that the keys to happiness were austerity and simplicity, and he had no use for abstract philosophy or religion, which, in his view, had nothing to do with the real world.
According to Cicero, a brave citizen once attempted to convince Diogenes of the existence of the gods by pointing to a series of paintings depicting sailors who had miraculously survived shipwrecks and arguing that the gods must exist and must care about people for so many to have made it safely to shore.
“See how many have been saved by their prayers to the gods!” the man declared.
Diogenes replied, “I see those who were saved, but where are those painted who were drowned?”
In other words, the paintings didn’t prove the existence of the gods because they didn’t tell the whole story. The paintings depicted only the shipwrecked people who survived and omitted the shipwrecked people who drowned.
The Diogenes story may not be true, but its point clearly is. If you only count the survivors, of course, everyone seems to be saved. An accurate count needs to include those who did not survive.
Survivorship bias comes up a lot. Consider mutual funds. Investment managers like to tout the successes of their mutual funds by showing long track records of success, but they almost always neglect to mention the mutual funds that are not on the list because they lost so much money that they went belly up and no longer exist. The survivorship bias makes it look like all investment funds perform great because the long-gone losers aren’t included in today’s marketing materials.
David McRaney of the You Are Not So Smart podcast described why survivorship bias is so easy to miss:
After any process that leaves behind survivors, the non-survivors are often destroyed or muted or removed from your view. If failures become invisible, then naturally you will pay more attention to successes. Not only do you fail to recognize that what is missing might have held important information, you fail to recognize that there is missing information at all.
What does this have to do with the Berkeley study of long-term marriages?
As lovely as it is too know that couples in long-term marriages become kinder to each other over time, what you don’t see is what happens to the couples whose marriages didn’t last into the long term.
It is entirely possible that long-term marriage doesn’t make couples kinder to each other, but rather spouses who continually treat each other better are more likely to have a long-term marriage.
It is not hard to imagine that spouses who treat each other with anger, contempt, disgust, domineering behavior, or defensiveness are not likely to stay together, while couples who treat each other with interest, affection, humor, enthusiasm, and validation are more likely to have a long and happy marriage.
So, what’s the bottom line? It’s what your mother always told you: it’s nice to be nice, and the nicer you are to other people, the nicer they will be to you. And that advice holds for anyone with whom you have a long-term relationship, including your spouse. Which isn’t such a bad lesson at all.