Among the challenges encountered in passing and implementing President Barack Obama’s signature health care reform law has been the public’s perception of what it means. A new study released today finds that many Americans — particularly those the new law was intended to help most — may not have basic knowledge about the law or health insurance in general.

The study, published Monday in the Proceedings of the National Academy of Sciences, used a nationally representative survey of 6,000 respondents and found that half of them were unaware of the exchanges set up for people to find and purchase health plans and that more than 40 percent could not accurately describe a deductible. People who were earning just above the federal poverty level performed worse on questions about the health care law and health insurance in general than people in the top income category did.

“I think the take-home message is we find there are very low levels of preparedness” for the Affordable Care Act, said Silvia Barcellos, the author of the study and an economist at the University of Southern California Dornsife Center for Economic and Social Research. She said an area of particular concern is that the levels of knowledge were often lowest among people who are uninsured or low income and therefore are the target population for the new exchanges.

“If these exchanges are to work, we need some policy responses to help these people make good choices on the exchanges,” she said. While the study was done shortly before the exchanges opened and the respondents are being surveyed again to see how their knowledge changes over time, Barcellos said she is not optimistic that the numbers from the study will have improved by now.

“There was already substantial press coverage about health care reform and the exchanges that were about to open, and here we found very low levels of information among the population,” she said.

Leighton Ku, director of the Center for Health Policy Research at the Milken Institute School of Public Health at George Washington University and an executive board member of the Health Benefit Exchange Authority, which was involved in setting up the exchanges for Washington, D.C., called the findings important “but not entirely unexpected.”

“There could be some serious problems in trying to implement the Affordable Care Act because there are many provisions people don’t understand as well as many basic concepts they have difficulty understanding,” he said.

Ku pointed to a similar study being performed by the Urban Institute. In a paper published in December, it similarly found that most Americans — especially those who were uninsured but even those who were — were not confident that they understood basic terms of health insurance.