The technologists of Silicon Valley who gave us technology’s many forms, are reaching a consensus that the benefits of screens as a learning tool are overblown, and the risks for addiction and stunting development are high. Parents, increasingly concerned about limiting screen time for children, have also created a new job for nannies, that of screen police.

Concern about tech from those working in technology is not new. Those like Bill Gates and Steve Jobs sounded alarms and banned cellphones and iPads for their children. But the past year has produced many findings about the negative impact of cellphones, computers and social media, particularly about what these technology gadgets do to the human brain.

Those who developed the uses of technology thought they could control it but now find it is beyond their power to control. The failure of recent attempts by the leaders of social media to correct various aspects of the technology involved in the more egregious fallout from their sites is a case in point.

Parents fear that their children are being manipulated by techniques that go directly to the pleasure centers of the developing brain. Psychologists working for the companies make the tools phenomenally addictive, being well-versed in the field of persuasive design — influencing human behavior through the screen.

Facing the difficulty of limiting screen time — especially cellphone use — for their children, parents are confronted by their own involvement with these devices. Those who strive for no screen time at all may find the rules harder to follow themselves. Nanny agencies across Silicon Valley report that parents are asking nannies to sign no-phone-use contracts.

At a time when many working parents use cellphones as a way of keeping track of their children, losing that means of control is another source of anxiety. Those with the means can hire someone else to do it — hence the new nanny contracts. But there are many for whom that is not an option. It is clearer than ever that technology in its many forms has become a kind of child minding in an era of parental stress.

Anxiety about screens also points to a more extensive difficulty parents may have about setting limits for their children. It is parents who provide the cellphones, computers and other tech gadgets, yet they seem to feel a loss of control over the rules they want followed. Part of the difficulty is the peer group influence both on parents and the children themselves. A mother who resisted making an iPad available for her son found that he was the only one in his class without one.

The new concern about children’s screen use points to yet another potential signpost of economic inequality. Only recently the concern was that economically advantaged children would have access to the internet earlier, gaining tech skills and creating a digital divide. Increasingly, children have been asked to do homework online, while only two-thirds of people in the country have internet service.

Now, with the increasing panic about the impact of screen time on children, there is the possibility that the children of poorer and middle-class parents will be raised by screens, while the children of those well off will go back to appropriate toys and greater human interaction. The companies that make technology products compete to get these products into schools and target students at an early age. Unfortunately, many schools do not have the resources for extracurricular activities and the use of screens fill the gap.

Is the devil in the screens themselves, or in the way the content is designed and provided?

— Elaine Heffner, LCSW, Ed.D., has written for Parents Magazine, Fox.com, Redbook, Disney online and PBS Parents, as well as other publications. She has appeared on PBS, ABC, Fox TV and other networks. Dr. Heffner is the author of “Goodenoughmothering: The Best of the Blog,” as well as “Mothering: The Emotional Experience of Motherhood after Freud and Feminism.” She is a psychotherapist and parent educator in private practice, as well as a senior lecturer of education in psychiatry at Weill Cornell Medical College. Dr. Heffner was a co-founder and served as director of the Nursery School Treatment Center at Payne Whitney Clinic, New York Hospital. And she blogs at goodenoughmothering.com.