Others, such as psychologist and chairman of the School of Psychology at the University of Sydney, Alex Blaszczynski, believe it's a sensation triggered by electrical signals. "I expect it's related to some of the electrical signals coming through in a transmission, touching on the surrounding nerves, giving a feeling of a vibration, " Professor Blaszczynski said. "I expect what's happening is that it is causing some physiological effect." Liam Rasmussen of the Gold Coast said he experienced phantom vibrations once or twice a day when he was expecting a call or a text message. "I reach into my pocket as a sort of a reaction to thinking I felt a vibration, only to find I haven't actually received a message," Mr Rasmussen, who is a technical specialist with Swimming Australia, said.

"I get the impression that you are expecting a text message, and the slightest bump makes you think your phone is vibrating." Jason Murray, a web developer at SBS in Sydney, said he also experienced phantom vibrations once or twice "every couple of days" and got them the most when he was expecting a notification on his mobile. "I think it's just sort of a mental thing," he said. He believes they could be occurring due to "a bit of friction" in his jeans pocket. Professor Blaszczynski said he believed the vibration people felt was not "phantom" nor related to an addiction but "a real sensation" similar to what occurs when you place your mobile near a speaker and hear a buzzing sound when it's communicating with a tower. That sound, caused by electromagnetic interference (EMI), occurs even when a mobile isn't receiving a text message or ringing, and it can often happen when the mobile is doing what is known as a "hand shake" with a mobile tower, he said.

The "burst of electrical activity" in that hand shake affects skin nerves, causing transcutaneous muscle stimulation and giving the impression of a vibration, he believes. He does not believe it causes any great harm to our bodies and stresses that he has not studied the phenomenon. "If you are really perturbed by [the sensation], simply hold [your mobile] away from your skin," Professor Blaszczynski suggested. Putting your mobile in a coat pocket or leather case would mean "significantly less" vibrations felt, he added. A colleague of Professor Blaszczynski at the University of Sydney, Professor Gerard Goggin, chairman of the Department of Media and Communications, believes that phantom vibrations occur when one is expecting "alerts and notifications" or a call or text. "Mobiles are very much a part of our lives, " he said. "In that sense they become an extension of your body."

Checking them therefore becomes almost like a reflex, regardless of whether they were ringing or vibrating, he said. What the studies say Of the two studies Fairfax Media could find related to the topic, the more recent, published on December 15, 2010, concluded that the sensation, or what it called "phantom vibration syndrome", was "common among those who use electronic devices". The study found that the prevalence of phantom vibrations in a population of medical staff using pagers and mobiles was nearly 70 per cent. The sample size was 176. Of the 169 participants who answered a question, 115 reported having experienced phantom vibrations, it said.

The study suggested its cause might result from "a misinterpretation of incoming sensory signals by the cerebral cortex" - the thick sheet of cells on the outside of the brain. "In order to deal with the overwhelming amount of sensory input, the brain applies filters or schema based on what it expects to find, a process known as hypothesis guided search," the study said. "In the case of phantom vibrations, because the brain is anticipating a call, it misinterprets sensory input according to this preconceived hypothesis. The actual stimulus is unknown, but candidate sensations might include pressure from clothing, muscle contractions, or other sensory stimuli." The other study, a graduate thesis published in 2007 on Emotional and behavioural aspects of mobile phone use by David Laramie, surveyed 320 adult mobile phone users and found that two-thirds had experienced phantom rings. What do you think causes the sensation? Have you experienced it? What have you done to prevent it?

This reporter is on Facebook: /bengrubb

