WASHINGTON — When it comes to health insurance, it seems most Americans want the impossible: low cost and unlimited choice of medical care.

"All of us would like cheap insurance with no restrictions," said Mark V. Pauly, a professor of economics at the University of Pennsylvania and a national expert on the economics of health care. "Even grown-ups are still teenagers when it comes to health insurance."

Pauly's comments came Wednesday during a hearing of the Joint Economic Committee, chaired by Sen. Bob Bennett, R-Utah, who is spearheading inquiries into ways to give consumers more health insurance options — and to control costs.

"Many consumers would like to have greater choice and control of their health care and health insurance coverage," Bennett said. "They know from their experience with many other types of goods and services that choice and competition helps match their different tastes and preferences to those options providing the best value."

Choice these days is being described in terms of reimbursement plans or health saving accounts. In theory, young healthy people could shop for lower-cost insurance that offers less coverage, but because they are low-risk, they would not need the full menu of benefits.

Older people and those with chronic diseases would choose the full menu and pay more for it, being deemed by the industry to be high risk.

Economists testified that the theory holds that if the young and healthy opt out of the current system — one where low and high risks are now averaged out among all participants in the plan so that high- and low-risk participants pay the same — then there will be fewer dollars in the high-risk pool, pushing costs for the high-risk premiums higher and higher until the system collapses.

Experts call it a "death spiral," and on Wednesday they debated whether it could happen if health insurance plans are opened up to a suite of new choices.

James Cardon, a professor of economics at Brigham Young University, argued that no one really knows what will happen, and that free markets should "provide the final test" and that "death spiral concerns are exaggerated."

"Health economics is a very challenging field, and the models and language involved tend to induce headaches," Cardon said. "After all the analysis, markets will provide the final test: If (health savings accounts) work, then they will become popular. If they do not work, then they will disappear."

The policy debate is more than just an intellectual exercise. Both Democratic presidential nominee John Kerry and President George Bush have waded into the debate of how to make health insurance more affordable.