Tween girls who spend much of their waking hours switching frantically between YouTube, Facebook, television and text messaging are more likely to develop social problems, says a Stanford University study published in a scientific journal on Wednesday.

Young girls who spend the most time multitasking between various digital devices, communicating online or watching video are the least likely to develop normal social tendencies, according to the survey of 3,461 American girls aged 8 to 12 who volunteered responses.

The study only included girls who responded to a survey in Discovery Girls magazine, but results should apply to boys, too, Clifford Nass, a Stanford professor of communications who worked on the study, said in a phone interview. Boys' emotional development is more difficult to analyze because male social development varies widely and over a longer time period, he said.

"No one had ever looked at this, which really shocked us," Nass said. "Kids have to learn about emotion, and the way they do that, really, is by paying attention to other people. They have to really look them in the eye."

Source: CNN