The Gerontological Society of America, in a study released yesterday at a hearing of the House Select Committee on Aging, challenged the idea that the federal government is spending too much on the elderly at the expense of the nation's children.

The society, a professional organization for research on aging, contended that the concept of generational conflict is based on a misunderstanding of family relationships.

The generational competition thesis asserts that federal spending for the aged for Social Security, Medicare and other benefits is storing up a tremendous burden of future debt that will have to be paid by today's children when they are grown and that today's children are losing out in the competition for funds that might combat ill-health and improve living standards.

Supporters of the generational-competition thesis point to the fact that in recent years, the proportion of poor among the elderly, once the highest for any group in society, has fallen to 12.4 percent, while poverty among children has risen to 21 percent. Yet, they point out, federal outlays for the elderly in fiscal 1985 were recently estimated at $245.5 billion by the Congressional Budget Office, while federal outlays to families with children totaled $90.4 billion.

The Gerontological Society paper contends that using federal spending comparisons is an artificial way of looking at social issues, fostered in some cases by those whose real purpose is to cut "virtually all public efforts directed at meeting family and individual needs."

Reps. Mike Synar (D-Okla.) and Edward R. Roybal (D-Calif.), chairman of the committee, said at a briefing on the report that there is little likelihood that if programs for the aged were cut, Congress and the administration would be willing to spend more to help the young. Roybal said many of those backing the young-versus-old theory are using it as "their excuse to attack Social Security."

In families, persons of all ages give and receive tremendous amounts of money and care, the society paper argues; federal spending is only a small portion of the total and should not be viewed separately from all other forms of support.

For example, it says, the vast bulk of support for children for their first 20 years or so of life comes from their parents and from state and local governments in the form of schooling. Thus, according to one study cited, assuming a value of $6 an hour for housework and child-care, transfers of wealth within families -- mainly from parents to children -- were worth $709 billion in 1979, the equivalent of 30 percent of gross national product and a far higher amount than spent by the government for the elderly.

Looking only at the amounts passing through the federal budget, the paper says, gives a distorted view of what society is doing for different groups. Spending for the aged looks big because society has decided to fund it through public mechanisms, primarily Social Security and Medicare.

The paper argues that if were not done that way, families somehow would have to meet the costs of sustaining the elderly, and the burden would fall heavily -- and often inequitably -- on their adult children.

In addition, the young-versus-old theory is based on exaggeration of the prosperity of the aged, the paper argues. While the poverty rate for the elderly is lower than for the population as a whole, 12.4 percent versus 14.4 percent, the paper notes there is a big cluster of aged just above the poverty line, known as the "near-poor," with incomes under 125 percent of the poverty line. Looking at the poor and near-poor combined, the figure for the elderly jumps to 21.2 percent, while the figure for society as a whole increases to 19.4 percent.

Eric Kingson, assistant professor at the University of Maryland and principal author of the report, also said the young-versus-old theory assumes a "zero-sum game" in which there will be no economic growth. He said increases in productivity will provide more money over coming generations to improve living standards for the young without taking away from the old.