A prekindergarten class in San Francisco. A study found preschoolers benefited when their parents received texts with guidance on how to help them.

With research showing language gaps between the children of affluent parents and those from low-income families emerging at an early age, educators have puzzled over how best to reach parents and guide them to do things like read to their children and talk to them regularly.

A new study shows that mobile technology may offer a cheap and effective solution. The research, released by the National Bureau of Economic Research this month, found that preschoolers whose parents received text messages with brief tips on reading to their children or helping them sound out letters and words performed better on literacy tests than children whose parents did not receive such messages.

Pediatricians are now advising parents to read daily to their children from birth. Some communities are developing academic curriculums for home visitors to share with parents of babies and toddlers, while other groups are mounting public information campaigns for parents on the importance of talking, reading and singing.

But many of these efforts do not necessarily target parents at the moments when they are most likely to use the information.

“What’s really cool about this is that the messages reach parents at a time when they can act on them,” said Todd Rogers, an assistant professor of public policy at Harvard University, who was not involved in the research. “It’s not just about getting messages to parents, but giving them in a timely way to serve to remind parents of things they already know and already intend to do.”

The study’s authors, Benjamin N. York, a Stanford University doctoral student, and Susanna Loeb, a professor of education at Stanford, followed 440 families with 4-year-olds enrolled in public preschool in the San Francisco Unified School District last year. The vast majority of the parents had low incomes.

Half of the parents received thrice-weekly texts for eight months with messages like “By saying beginning word sounds, like ‘ttt’ in taco & tomato, you’re preparing your child 4 K,” or “Let your child hold the book. Ask what it is about. Follow the words with your finger as you read.”

The messages were developed in consultation with Molly Wertz, executive director of the Bay Area branch of Raising a Reader, a nonprofit that distributes books to low-income families, and Helen Maniates, a reading expert at the University of San Francisco.

The other half of the parents received one text message every two weeks with simple information about kindergarten enrollment or vaccinations.

Carla Bryant, chief of early education for the San Francisco Unified School District, said she understood how the text messages might spur action in overwhelmed families.

“If I got a little text saying, oh, ‘Today have you had a conversation with your child about x, y and z?’ ” Ms. Bryant said, “I would be like, oh my goodness I need to do that. Let me just do it.”

Parents who received the literacy texts were far more likely to report pointing out rhyming words or describing pictures in a book to their children than those who received the more general texts. Teachers, who were not aware of which parents were placed in which group, also reported that those who received the literacy tip messages asked more questions about their children’s lessons.

And when the children were given tests of letter and sound recognition, those whose parents had received the literacy texts had scores that indicated they were about two to three months ahead of those children whose parents had received only the general information texts.

Because 80 percent of the families already had unlimited text messaging plans on their cellphones, the cost of the program was less than $1 per child. That compares to home visiting programs that can cost close to $10,000 per child and require that families devote a considerable amount of time during an intensive period.

Other groups are also trying to encourage early literacy through text messages to low-income families. Too Small to Fail, a joint effort of the nonprofit Next Generation and the Bill, Hillary & Chelsea Clinton Foundation that is aimed at closing the language gap across the country, is working with Text for Baby, a nonprofit that sends health care tips to parents, to add messages about talking, singing and reading.

“We didn’t have the technology to reach parents in this mass way in the early 1990s,” said Ann O’Leary, the director of Too Small to Fail, “and we didn’t have evidence of behavioral science and how all these nudges might have an impact.”