Would you give your child a toy that harmed its brain? That question faces every parent this week, as the start of the present-buying season collides with warnings from experts that a serious deterioration in children’s health may be partly caused by the electronic domination of the toy shop.

Today’s children endure a “toxic childhood”, said the public letter from 110 academics, educators and writers last week. To deep cleanse it they need “real play (as opposed to sedentary, screen-based entertainment), first-hand experience of the world they live in and interaction with the adults in their lives”.

It sounds a simple enough prescription. But according to Madeleine Portwood, an educational psychologist, more and more small children seem not to receive it. “Three years ago we screened 400 three-year-olds,” she says. “Over 50% of them . . . could not balance, walk sideways, jump with two feet, hop. We gave them 15 minutes of exercise a day. After six months, only 3% had problems. They would have loved doing the exercise at home but other things seem to have got in the way.”

Those other things, she believes, include not only more time in front of a screen but also the trend towards electronic toys, which over-reward the child for pushing buttons. Such toys also offer children no chance to discover the physical properties of objects — discoveries which form the building blocks of logical thinking, says Michael Shayer, a psychology professor.

He recommends no more than an hour’s screen time daily for a healthy growing brain. From the ages of six to 16 experts agree that children should have two hours of physical activity a day.

Shayer’s study showing that today’s 11-year-olds have the thinking skills of eight-year-olds in 1976 was widely quoted last week as evidence of real deterioration in the past 25 years. But this decline has not occurred equally. Girls’ scientific abilities, never high, have fallen slightly. But the dramatic collapse is among boys.

And it is boys’ play, says Shayer, that has moved so relentlessly from the treehouse and riverbank to the sofa and the screen: “Boys used to have mechanical toys, build dens, explore the physical properties of materials . . . If you are looking at a screen, you are in a one-dimensional, pre-prepared reality. You don’t have a chance to create and discover your own.”

In fact the “reality” of electronic toys may also be prompting an unprecedented emotional confusion, according to Sherry Turkle, a professor at the Massachusetts Institute of Technology. “Children’s attitudes to what’s alive and what’s not alive are shifting. It started with Furbies and Tamagotchis, but now there are these sophisticated robots that reach out to you. Children are starting to make a new ‘sort-of-alive’ category for them. If you say to them, ‘Is this toy alive?’, they say, ‘I take it to bed, it might want to hug me’. The child relates to it as if it was real.”

Of course electronic interaction can have benefits, she adds: “Young people can use the web and messaging to try out aspects of themselves and to practise their social skills. I’ve always been very techno-happy: when other people were saying ‘Oh my God’ about computers I was saying ‘No, it’s a new kind of creativity’. But I don’t feel that way about this.”

Children have always imagined dolls were alive, she adds. But that kind of imagining, says Turkle, is not the same. Dolls are available to be punished one minute and loved the next, to be filled with whatever children put into them: “Robots are different: they come with their own agenda. Because children think of them as ‘sort of alive’ they expect interaction. They expect the toy to care for them back.”

The fear here is that children’s emotional development may be distorted. And it is in the field of mental health that the evidence is strongest of a sea change. A study based at the Institute of Psychiatry in London has shown depression and disturbed behaviour among adolescents almost doubling since 1976.

The study is being extended to include younger children, who, like teenagers, are subject to many pressures, including those identified by the experts protesting last week: more tests, junk food, lack of freedom. Without a window into children’s brains, which is almost impossible, since few parents would agree to brain scans, and no researcher dare to request them, it is impossible to tell what chemical changes might be taking place.

Nevertheless, says Baroness Greenfield — a professor of pharmacology at Lincoln College Oxford and a key voice calling for a government investigation into what is happening to children’s brains — electronic entertainment must be a prime suspect. “We know experience leaves its mark on the brain,” she says. “We are bringing our children up in a very different environment from 20 years ago, where they press a button and get immediate feedback, where they spend hours in front of a screen. How can that not have a profound effect?”

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