Here’s a simple but interesting exercise for you to try at home. Take any one household activity in which both you and your spouse participate. This could be any activity—such as buying groceries, helping kids with the homework or taking care of household chores—where the two of you share the responsibility of making sure the activity gets done.

You can also try this exercise at work. Take any group project where a number of people are jointly responsible for completing a task. Ask individuals to estimate their percentage contribution to the total task, add up the individual answers, and you will find the total is far greater than 100%.

People often claim more credit than is legitimately attributable to them. They do this not to be unfair to the other participants in the joint effort, but because they genuinely believe that their contribution was higher. This bias for over-claiming credit is a fairly widespread phenomenon and even academics and Nobel Prize winners have been its victims. In a famous case, joint winners of the 1923 Nobel Prize for medicine over-claimed credit for the discovery of insulin for themselves, minimizing the contributions of their partner.

Couples often fight over household chores, each blaming the other for not pulling their fair share. Credit over-claim has even been cited as a reason why some joint partnerships between firms fail—each party feels that they are being taken advantage of in the relationship because of lack of equal contribution by their partner. Research has also shown that the greater the degree of over-claim, the less willing the parties are to cooperate in the future.

Why do people over-claim credit in joint tasks? One of the primary drivers seems to be the self-serving bias. While we will get into the details of this bias in another column, the basic idea behind this bias is that people tend to focus on facts and reasons that serve themselves. People have a natural tendency to view things through a lens that shades things based on the viewer’s role in the situation. People first assess their preference for a given outcome and then assign different weights to the components of the overall task in such a way that the assigned weights tilt the outcome to what they prefer to see. In doing so, they are not trying to be dishonest—they are simply prejudiced because of their own bias.

Is there any way to minimize this problem of credit over-claim? While it may not be possible to completely eliminate the credit over-claim, one can reduce the degree or extent of over-claim by forcing the individual to first come up with an assessment of other members’ contributions. This way, we “unpack" the contributions of the rest of the group, making it more difficult for the individual to glaze over those contributions. Taking the other person’s perspective in assessing relative contributions can also help. Finally, we ought to keep in mind that when a person over-claims, they are not trying to deceive us or hurt us by minimizing the significance of our contributions. Because of the self-serving bias, they genuinely believe that they contributed more. The bias becomes more severe when there is ambiguous information that is open to interpretation by the parties.

So, the next time you want your spouse to give you credit for your portion of the chores that he seems to undervalue, first make him aware of the credit over-claim bias and then ask him to carefully list specific actions or contributions of both parties before making a judgement about relative contributions.

Praveen Aggarwal is an associate professor of marketing at the Labowitz School of Business & Economics at the University of Minnesota Duluth and Rajiv Vaidyanathan is a professor of marketing and director of MBA programmes at the University of Minnesota Duluth.

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