AUSTIN, Texas — As couples mature together, they often grow apart in their level of interest and skill in handling their finances. A disparity in financial literacy that may be small or even nonexistent at first can increase over time depending on how much responsibility one partner undertakes, according to researchers at The University of Texas at Austin and the University of Colorado-Boulder.

Adults are often ignorant about the most basic facts about money, such as the effects of compound interest and inflation, or how long it will take to pay off a debt. Many times, financial education to reduce financial illiteracy is ineffective. Why?

New research recently published in the Journal of Consumer Research showed that when it comes to skill in handling finances, people evolve — or stagnate — on a “need-to-know” basis, driven in large part by relationship roles.

“We argue that people pay attention to what they need to know, when they need to know it,” said lead researcher Adrian F. Ward of UT Austin’s McCombs School of Business, who launched the study to better understand why so many Americans lack money know-how — and why financial education is so ineffective at solving this problem.

For couples, this critical “need to know” hinges on how partners use each other as external sources of expertise. The research shows that early in relationships, when couples assign the role of a “household CFO,” they unknowingly set each other on divergent paths — the responsible partner embracing and growing in financial knowledge over time, as the delegating partner’s financial ability and interest stagnates.

The study found that couples usually begin these paths on equal footing, and the partner who initially accepts financial responsibility has no greater financial experience, expertise, or aptitude than the one who does not.

But the longer couples stay together, the more the partner who is completing financial tasks grows in proficiency — even more so in households where that partner takes on a much larger share of these duties.

“We interpret our findings to say that the assignment of financial responsibility causes the two members of the couple to go on different trajectories for a lifetime,” Ward said. “The longer the relationship, the greater the gap in financial literacy between the household CFO and the non-CFO.”

Although such specialization is natural — even practical — researchers say that it could spell trouble for those who have delegated the financial role. In fact, the study found that partners with low financial responsibility actually decline in financial literacy over the years.

So after divorce or widowhood, when these partners are suddenly thrust into the financial driver’s seat, they may be unable to successfully navigate this domain. Indeed, when researchers asked them to make financial decisions or even read new financial information independently, they struggled.

Previous research has tried to explain financial ignorance by analyzing individual differences, such as personal interest or prior knowledge, but Ward says what consumers learn is best understood in a social context.

“Differences in what partners know, learn, and even notice are not just reflections of each individual’s idiosyncratic preferences, but are in fact created by the existence of the other person,” he said.