Young people’s brains are failing to develop properly after being overexposed to the cyber world at an early age, it was claimed.

Baroness Greenfield, professor of pharmacology at Oxford University, said a decline in physical human contact meant children struggled to formulate basic social skills and emotional reactions.

She criticised the “unhealthy” addiction to Twitter among some users who resort to increasingly nasty outbursts under the “sanitised and often anonymous guise of the web”.

In an interview with The Daily Telegraph, she also raised concerns over the “narcissistic” nature of sites such as Klout, which measures users’ popularity and influence on social networks.

The comments come just 24 hours after teachers warned that over-exposure to technology was damaging children’s ability to concentrate in the classroom.