The "gender gap" that worries Republican political strategists and clouds President Reagan's chances for reelection looks more and more like a deeply rooted trend that political scientists think will be tough for Reagan to turn around.

With one exception, more than a dozen studies presented at the American Political Science Association convention here over the weekend suggested that women's aversion to Reagan and his policies is pervasive, complex and probably linked to psychological and economic changes that are nearly irreversible in the short term.

The one loud dissent came in a cross-cultural analysis of elections in the past decade in Italy, West Germany, the Netherlands and the United States. It concluded that when differing levels of "religiosity" of men and women are factored out, "women in western democracies are not prone to vote their perceived interests as women."

The contention that "there is no discernible relationship between gender and voting" came from two political scientists at Texas Tech University, Lawrence C. Mayer and Roland E. Smith, and many of the others at their panel today were skeptical of it.

Public opinion polls in the past three years consistently have shown a gender gap in which Reagan and the Republicans score six to 18 percentage points lower among women, but the political scientists are far from agreement in explaining the phenomenon.

Two major theories seem to be evolving--neither of them very comforting to Republican hopes that the gender gap will disappear quickly.

One is that women traditionally are more concerned about questions of peace and well-being, and that Reagan's rhetoric and actions set off alarm bells by emphasizing armaments and curbs on welfare, feeding and health programs.

"Women's traditionally stronger involvement with the peace and compassion issues has been heightened by Ronald Reagan's seeming insensitivity to these issues," Jean Bethke Elshpain of the University of Massachusetts told a plenary session on "Gender Politics in the 80s" Saturday night.

A different--and somewhat conflicting--explanation is that women as a group see themselves as particularly vulnerable to Reagan's policies and are reacting against them out of self-interest.

"Women's political behavior can best be understood if we think of women as a disadvantaged or vulnerable minority, a group disaffected because of its status of dependency," John C. Blydenburgh of Clark University and Roberta S. Sigel of Rutgers University said in an analysis of the 1982 election polls.

"In the case of American women," they wrote, "the drive for protection focuses heavily on the economic sphere because here women's inequality is not only particularly notorious but also life-threatening.

"Women, therefore, tend to favor all those policies designed to reduce their economic vulnerability and that of their offspring as well as that of the poor and helpless in general. What frequently has been attributed to women's greater tenderness or softheartedness, we instead attribute to their status as a vulnerable minority."

The phenomenon of Reagan's lagging support even among more affluent, better-educated women (who give him significantly less backing than their spouses) was explained in similar terms by Laura Katz Olson of Lehigh University. Referring to the risks of divorce and widowhood, she said, "Even those who are comfortably fixed are only one man away from poverty."

Steven Erie of the University of California-San Diego adds another element to the self-interest argument. He noted that not only are women the main recipients of most of the income-linked welfare services that have been cut in Reagan's budget, but they are concentrated among the providers of those services.

"Seventy percent of all women professionals and managers, but only 33 percent of the males in those categories, work in the fields of health, education and welfare" that felt the brunt of the Reagan economies, Erie said. "Reagan's attack on human-service providers is a bread-and-butter issue for women."

Evidence for this view came in a study of 1982 voting by Susan J. Carroll of Rutgers University and Laurily K. Epstein of NBC News. Looking at exit polls in 23 states, they found that "the states with the largest gender gaps were characterized by high concentrations of working women, professionals and managers, and the well-educated."

For all these reasons, there were many predictions here that the women's vote will become an increasingly important political factor, and that women will increase their presence in government.

U.S. Court of Appeals Judge Abner J. Mikva told the political scientists that "the semi-permanent alignment of women with the Democratic Party" may be even more important in its consequences than the shift of blacks from the Republican to the Democatic Party in the New Deal."

"Women are not ghetto-ized," he said, "so the effects will be felt in the South, in the suburbs, in rural areas" and other constituencies where Republicans might otherwise enjoy a political advantage.

A number of studies detailed the difficulties women candidates face, particularly in the "image" area, where their efforts to display the "toughness" voters think is needed in office backfire by making them appear "strident" or unfeminine.

Noting that such GOP strategists as Sen. Richard G. Lugar (R-Ind.), chairman of the Republican Senatorial Campaign Committee, are seeking to recruit women candidates, researchers from Merrimack College pointed out that "since 1974, almost a dozen women candidates have challenged incumbent senators, and all have lost."

By contrast, Eugene Declercq, James Benze and Elisa Ritchie said that "in races for the House between 1974 and 1982, female incumbents won 96 percent of the time, a figure even higher than the 92 percent overall incumbency return rate in the House in that period."

Their conclusion is that the "gender barriers" that work against women challengers' establishing the right mixture of toughness and compassion turn into advantages when women display the combination in office.