The push for more single-sex instruction in public schools is based on weak, “misconstrued” scientific claims rather than solid research and may do more harm than good, according to a study published in the journal Science on Thursday.

The authors, a group that includes psychologists, child development specialists and a neuroscientist who specializes in gender, argue that while excellent single-sex schools exist, there is “no empirical evidence that their success stems from their single-sex organization,” as opposed to the quality of students, the curriculum or short-lived motivation that comes from “novelty and belief in innovation.”

Evidence is more clear that sex segregation increases gender stereotyping and legitimizes institutionalized sexism, the authors write. They call on President Obama to rescind regulatory changes spurred by the 2002 federal No Child Left Behind law that made way for more single-sex classes in public schools.

Civil rights debates have raged in recent years over whether single-sex classes in public schools represent a backslide in gender equality, or an opportunity for poor families to access promising gender-specific instruction typically reserved for rich families paying private school tuition. This latest study represents a new front in the battle by challenging varying interpretations of burgeoning brain research.

About 500 public schools nationwide offer single-sex classes, according to the National Association for Single Sex Public Education, based in Exton, Pa. That’s up from a handful a decade ago.

No Child Left Behind cites single-gender classes as one “innovative” tool to boost achievement. But anti-discrimination laws banned widespread use of such classes, allowing them only in certain instances, such as sex education lessons. A change in federal regulations in 2006 gave schools more flexibility, allowing boys and girls to be separated as long as classes are voluntary and “substantially equal” coeducational classes are offered.

The approach has gained popularity during an era in which school choice and experimentation are hallmarks of reform. Budget cuts have curtailed demand, though, with few schools able to invest in training or extra teachers to make the instructional changes, said Leonard Sax, director of the national association that advocates for and tracks single-sex public schools, who was critical of the study.

Despite small numbers, the study’s authors formed the American Council of Coeducational Schooling this year at Arizona State University as the first organization dedicated to advocating for co-ed schools as the best environment to prepare children for a co-ed world.

“Nobody is talking about how there’s no evidence to support” single-sex public schooling, said Richard A. Fabes, a director of the new council and an author of the Science article.

The authors cite as unfounded work by Sax that boys and girls, for example, respond to classroom stress differently because of differences in their autonomic nervous systems, which make boys thrilled by loud, energetic or confrontational teachers, such as “What’s your answer, Mr. Jackson? Give it to me!” while girls prefer to be approached by a gentler touch, such as “Lisa, sweetie, it’s time to open your book.”

Sax, a former medical doctor who has a doctorate in psychology, said he was looking for scientific explanations for differences in teaching styles he has observed in hundreds of single-sex schools, not offering fool-proof scientific justifications for single-sex education.

The best arguments for single-sex schooling are social justice arguments, he said.

“We live in a sexist culture,” Sax said. “Writing poetry and keeping a journal is something girls do. Boys are going to need something different than what girls need . . . to deconstruct that.”