A recent study showed that social networks like Twitter and Facebook are potentially more addictive than cigarettes or alcohol, and now we may have an idea why. A group of scientists from MIT in Massachusetts, IULM University in Milan and two other laboratories in Italy found that people showed physical and psychophysiological responses while using Facebook similar to those exhibited by people while playing a musical instrument or engaging in other creative activities. Beyond wanting to use Facebook for obvious reasons such as keeping up with friends and sharing photos, people may actually be seeking out the chemical responses they experience while browsing social networks. Read on for more.

The team of scientists measured skin conductance, blood volume pulse, electroencephalogram, electromyography, respiratory activity and pupil dilation in 30 subjects as they viewed photos of nature, attempted to solve math problems and then as they browsed Facebook. The results showed a clear psychophysiological pattern.

"Statistical analysis of the psychophysiological data and pupil dilation indicates that the Facebook experience was significantly different from stress and relaxation on many linear and spectral indices of somatic activity," the group's report states. "Moreover, the biological signals revealed that Facebook use can evoke a psychophysiological state characterized by high positive valence and high arousal (Core Flow State)."

As a result, the scientists hypothesize that the rapid growth being seen among big social networks can be attributed at least in part to positive physical and psychophysiological responses users experience while browsing sites like Facebook.