Two Heads Are Not Better Than One

Did we bother to discuss the wisdom of this enormous investment with anyone else -- a financial planner, perchance? A savvy friend? An architect or engineer? Of course not.
03/12/2012 12:49 pm ET Updated May 09, 2012

Once we saw the house, we knew that it would be just perfect for our recently blended family. Room for three not quite adult but definitely not young children. Great kitchen. A basement where one could fantasize about happy adolescents (first fantasy) playing pool and ping-pong (second fantasy) while engaging in wholesome evening activities (third fantasy). And office space for two.

After all, we had been looking for a new home for months in what felt like a Bataan march through too many other homes. Once we walked through this one, we came, we saw, we put in a contract.

Did we bother to discuss the wisdom of this enormous investment with anyone else -- a financial planner, perchance? A savvy friend? An architect or engineer?

Of course not.

We are two relatively educated people. My husband is a doctor (and we all know how smart they are) and went to Princeton (could anyone actually be smarter than that?) and I am no slouch.

It was the height of the boom. Put simply, like millions of others, we paid too much.

The fact that this turned out to be a great house and a bad investment is not the point here. The mortgage meltdown and financial crisis has yielded far more powerful stories than ours -- many with really tragic outcomes, which ours emphatically isn't.

No, the point here is that quite unwittingly, my husband and I illustrated the central finding of some new research published in Psychological Science, a journal of the Association for Psychological Science. In "The Cost of Collaboration: Why Joint Decision Making Exacerbates Rejection of Outside Information," two psychologists from the University of Pennsylvania's Wharton School shed some fascinating light on the process of decision-making when only two people are involved.

The headline? Somehow, when we are in a "dyad," we are likely to be so enthralled with our own mutually reinforcing judgments we tend to be very unreceptive to outside advice.

Even when it is right and our judgment is wrong.

"People in general are not very open to the input of others. In fact, we could argue that they are not open enough to the input of others," says Julia A. Minson, a social psychologist who was one of the authors of the paper. "In our study the dyads made that error to a greater extent than individuals. Before we were about to launch the study, I talked to a former collaborator. She said don't bother. Individuals already take so little input from others, it isn't possible that dyads take less."

But in fact, they do.

Minson and her collaborator, Jennifer S. Mueller, gathered 252 participants, sat them in a partitioned room and asked them to answer nine questions that had to do with US geography, demography and commerce. Questions like, "What percentage of Americans own pets?" (The correct answer is 63 percent) Or, "In the United States what percentage of homeless men are veterans?" (40 percent) were answered twice. The first time the participants worked alone and estimated the percentage. The second time they did it together after a discussion with a partner.

After their collaborative answer, an outsider came in. This "peer advisor" gave the dyad answers to the questions -- not suggesting if the answers were right or wrong but just giving additional input -- and then offered them the opportunity to change their answers. There was even a financial incentive for a correct answer. The participants were compensated with $10, and depending on their performance, they could receive up to a $30 dollar bonus for completing both rounds.

But the bonus decreased by $1 for every percentage point that any given estimate was off from the correct answer.

It didn't matter. Dyads were more reluctant than individuals working alone to revise their judgments, and as a result, their revised estimates were less accurate than they could have been had dyad members been more willing to accept peer input. They were also very reluctant to give any weight to outside estimates that were more accurate than their own.

But perhaps that means that even if my husband and I had talked to others and looked for other information, we still were in such a mutually reinforcing state that we might not have listened to it anyway. After all, we are all less likely to give weight to external information, so the information search going forward is closed. Even though this is a search that could, in the end, help us make a better decision.

Obviously we were not alone. Minson suggests that this way of thinking can be dangerous in all sorts of circumstances, from a couple making an investment to a company launching a product. "People feel better when they make a decision with another person," Minson explains. "Making a judgment together makes us more confident in the outcome, but that confidence comes with a cost."

When I was discussing this research with some women friends, I asked them about how this closed circle of the dyad might have played out in their lives. My friend Margie asked (of course in jest), "Hmmm ... isn't that how we ended up getting married in the first place?"