Facebook and Twitter generation have developed childlike desire for reassurance, experts say

Repeated exposure to social networking sites has left users with an “identity crisis”, similar to a toddler saying: "Look at me, Mummy, I’ve done this."

Baroness Greenfield, professor of pharmacology at Oxford University, believes the growth of internet “friendships” - as well as greater use of computer games - could effectively rewire the brain.

The effect could lead to a reduced concentration span, a need for instant gratification and the inability to make eye contact during conversations.

More than 750million people across the world now regularly use Facebook to share photographs and videos of their movements and thoughts.

Millions have also signed up to Twitter, the ‘micro-blogging’ service that lets members circulate short text and picture messages about their lives.

Baroness Greenfield, former director of research body the Royal Institution, said: “What concerns me is the banality of so much that goes out on Twitter. Why should someone be interested in what someone else has had for breakfast?

“It reminds me of a small child (saying): “Look at me Mummy, I’m doing this”, “Look at me Mummy I’m doing that”.

“It’s almost as if they’re in some kind of identity crisis. In a sense it’s keeping the brain in a sort of time warp.”

Literacy expert and author Sue Palmer said girls in particular believe they are a “commodity they must sell to other people” on Facebook.

She said: “People used to have a portrait painted but now we can more or less design our own picture online.

“It’s like being the star of your own reality TV show that you create and put out to the world.”