摘要：研究人员根据一个以一、二年级的小学生为对象的实验发现，有“数学焦虑症”的父母越帮孩子做数学作业，他们的孩子就可能数学学得越差，甚至孩子自己最后也会有“数学焦虑症”。

A common impairment with lifelong consequences turns out to be highly contagious between parent and child, a new study shows.

The impairment? Math anxiety.

Means of transmission? Homework help.

Children of highly math-anxious parents learned less math and were more likely to develop math anxiety themselves, but only when their parents provided frequent help on math homework, according to a study of first- and second-graders, published in Psychological Science.

Researchers tested 438 children from 29 public and private schools in three Midwestern states for math ability as well as math anxiety, at the beginning and end of the school year. Their parents completed questionnaires about math anxiety, and about how often they helped their children with homework.

So much for good intentions. The more the math-anxious parents tried to work with their children, the worse their children did in math, slipping more than a third of a grade level behind their peers. And the children’s weaker math achievements increased their nascent math anxiety.

“The parents are not out to sabotage their kids,” said Sian L. Beilock, a cognitive psychologist at the University of Chicago and the author of “Choke,” about anxiety and performance. “But we have to ensure their input is productive. They need to have an awareness of their own math anxiety and that what you say is important.”

For example, she said, comforting a homework-distressed child, by saying, “ ‘I’m not a math person either, and that’s O.K.,’ is not a good message to convey.”

The research results come as no surprise to Jennifer Hare of Aspers, Pa., who has a third grader and a sixth grader, and two more on the school runway. In college, Mrs. Hare, a daughter of math-anxious parents, switched majors just to avoid required math courses.

An exhausted soccer mom, she is still determined to help her math-challenged, math-anxious children. To hide her grimaces as she stares at quasi-algebraic word problems, she holds a piece of paper in front of her face. That does not fool them at all — maybe because she says she sometimes bursts out: “‘What are these teachers thinking? Are they nuts?’”

For decades, researchers have looked at the effect of high math anxiety, which, some studies show, can afflict 10 percent to 20 percent of adults. Math anxiety affects not only test taking and grades but also self-esteem and everyday computational skills. (How many gallons of paint for two coats of your living room? Can you convert a double-layer cake recipe into a triple-layer?)

Mark H. Ashcraft, an expert on math anxiety at the University of Nevada, Las Vegas, explains that the condition can feed upon itself. “On challenging math problems that require a lot of working memory, math-anxious people fall apart,” he said. Their working memory is consumed by worry and anxiety, “and they don’t have enough left over to do the math.”

Many adults identify middle-school algebra as the onset of math anxiety. Research has shown that it can begin earlier.

In a 2010 study, Dr. Beilock’s team found one significant factor, particularly for young girls: math-anxious elementary schoolteachers, almost 90 percent of whom are female.

But the effect of math-anxious, homework-helping parents is a newly discovered factor. Parental math anxiety is exacerbated whenever schools introduce new methods of learning math, said Harris Cooper, a professor of psychology and neuroscience at Duke University, who has studied the effects of homework.

“Educators can’t take math, turn it into Greek, and say, ‘Mom, Dad, will you help your kid with this,’ and not expect to get a ‘wha?’ ” he said.

On the Facebook page of The New York Times, Theresa Ellson of Sandpoint, Idaho, responding to a callout, described her anxiety while helping her daughters with Common Core math: “I’ve taken to labeling math homework by how many glasses of wine it takes me to peel myself off the ceiling after I’m done. ‘That was a two-glasser,’ after whatever it is we’re calling long division. And that’s for fourth-grade math homework.”

A small comfort: The homework-helping, math-anxious parents did not have a negative effect on their children’s reading ability, the new study said.

How can math-anxious parents help their children at math? Dr. Cooper suggests that parents of young children create a math-positive environment by modeling “math behavior.” The game plan: Tell your child, “‘You have your math homework, and I have mine,’” he said, and show them whenever you “count your change, calculate when dinner will be ready, look at prices in a grocery store.”

Then there are the extremes that Tara Sweeney went to.

Mrs. Sweeney, of Floral Park, N.Y., acquired her math anxiety in the third grade, when she had to stand in front of the class and recite multiplication tables. When her older son was in the third grade, she would scan his math homework and email it to her husband, who was working in Europe.

“He would conference-call us because I was so paralyzed with anxiety,” Mrs. Sweeney said. “I would yell, ‘I’m done with it, I can’t do it!’ ”

Finally she said to herself, “Math isn’t going away.”

So she studied the school’s math curriculum. She asked teachers for manuals and lesson plans and watched videos.

“Some of the other moms are annoyed at me,” Mrs. Sweeney said. “But I didn’t mind putting in that time, because I needed to feel confident. I don’t want my sons to be as math-anxious as me.”

“And,” she noted, “in the last year or so, I actually think the math has gotten a little easier.”