Home buyers are beginning to respond to expectations that inflation will stay low during the next few years by returning to more traditional mortgage financing patterns, according to a new study of mortgages and borrowers conducted by the U.S. League of Savings Institutions.

As a result, home buyers are making larger down payments and spending less of their total family income on housing, as well as opting more often for shorter-term loans. Such financing patterns were common during the 1950s and 1960s, but were abandoned by many families during the inflationary 1970s.

"The changes disinflation brought to the 1985 mortgage market are likely to remain as long as interest rates remain at subdued levels," league Chairman Gerald J. Levy said. "The inflationary financing mechanisms that were born in the 1970s will continue to fade, and home financing will be characterized by more traditional patterns."

The league's home-buyer study, released this week, is taken from data collected on 16,300 mortgage loans made by saving institutions in 46 cities during the April-to-June period last year. While providing a snapshot of national financing patterns, the study also offers profiles of the typical home mortgage and home buyers in the cities where the study was conducted.

The average U.S. home buyer last year was 35.8 years old, married and had a median income of $42,396, according to the study. Slightly more than half the home buyers surveyed had households of two people or less, and four out of every 10 home buyers were purchasing their first house.

By contrast, the average Washington home buyer was 37.3 years old, married and had a median income of $55,740. Similar to the national trend, slightly more than half live in households of two people or less and only three out of 10 were first-time buyers.

The most expensive housing in the nation was found in San Francisco, with a median sales price of $152,000. New York City was next, with a median sales price of $129,700, followed by Boston, $126,000; Los Angeles, $123,000; and Anaheim-Santa Ana-Garden Grove, Calif., with $122,000. The median in the Washington area, the point at which half of the homes cost more and half cost less, was $105,000.

The study also found that the share of American families who own their homes has continued to drop since 1980, and last year reached a 17-year low of 63.9 percent. Levy said that, despite the recent improvements in mortgage interest rates, the trend toward lower levels of homeownership proves that owning a home is becoming more and more difficult for many families.

In addition, twice as many home buyers took shorter-term mortgages than they did in 1983, in order to speed up the process of building equity in their homes, Levy said. U.S. league economist James Christian said this trend comes from home buyers' recognition that inflation cannot be relied on to provide automatic appreciation of housing values in most American cities.

According to the study, the share of home buyers who spent more than 25 percent of their monthly incomes on housing costs -- including mortgage principal and interest, real estate taxes, utilities and homeowners' insurance -- dropped sharply from 40.4 percent in 1983 to 33.5 percent in 1985, the lowest figure since 1977.

Christian said one of the reasons for the drop was the increasing number of home-buyer families with two incomes. Christian said that last year almost 70 percent of first-time home-buyer households with at least two adults had two incomes. Moreover, the contribution of those second incomes has grown. Christian said that for more than half of the two-income households, the second incomes accounted for more than 30 percent of the families' total incomes.

The median family income of the home buyers surveyed by the league last year rose to $42,396, up 18 percent from 1983 levels. First-time buyers had a median income of $35,964, a 22 percent increase since 1983.

The median price of the housing purchases surveyed also rose, from $65,000 in 1983 to $75,000 in 1985. Despite that increase, however, home sales, fueled by lower interest rates, rose to their highest levels since 1979.

The study found that the percentage of buyers who were first-timers had stayed even since 1983 but that, in general, the first-time buyers are older, wealthier and less willing than they were two years ago to take on mortgages that would eat up a disproportionate share of their income.

Home buyers across the board were older last year than ever before. The typical home buyer surveyed was nearly 36 years old, three years older than in 1977, and the typical first-time buyer was 30 years old, the first time the average age for that type of home buyer had crossed that age threshold.

The percentage of first-time buyers willing to spend more than 25 percent of their income on housing dropped sharply from 47.2 percent in 1983 to 38.1 percent in 1985.

Home buyers choosing shorter-term mortgages jumped from 6 percent in 1983 to 14 percent last year. Christian said the attraction was the rapid rate of equity build-up, which is nearly seven times as fast during the first five years for a 15-year mortgage as for a 30-year mortgage.

Christian said the survey showed that the housing market in the Washington metropolitan area "had not been as hot" recently as some other northeastern cities, but that, in general, borrowers here also are following the move toward more traditional financing patterns.

The median family income of those home buyers surveyed in Washington rose from $54,558 in 1983 to $55,740 last year. At the same time, however, the median price of houses sold dropped from $120,000 in 1983 to $105,000. Christian said that did not necessarily mean housing values here had depreciated, but simply that the median price of the houses sold during those years had dropped.

Fewer Washington families are willing to spend more than 25 percent of their income on housing expenses now than two years ago. In 1983, some 49 percent of households surveyed spent more than one-quarter of their earnings on such expenses, while last year that share had dropped to 32.2 percent.