Why using a mobile phone can be contagious Every person we observed used his/her phone at least once while one woman was on hers about half of the time. Individuals may see others checking their incoming messages and be prompted to check their own. He said the conclusions were a timely warning to people about mobile phone use. Asked what this showed about society's use of phones, Dr Kruger told The Daily Telegraph: "We need to get smart about smart phones. They can be a wonderfully useful technology, but we need to use them more carefully to make sure that they do not interfere with our in person social interactions. In their study, almost two dozen students in two groups, were observed "unobtrusively," who were seen socialising near an unnamed university campus. Researchers recorded every moment a person used their mobile phone in dining halls and coffee shops around campus between January and April lat year. Students, who did not know they were being watched, sat in pairs at tables for as long as 20 minutes and documented their phone use at 10-second intervals. Dr Kruger, from the university's School of Public Health, Population Studies Center and the Institute for Social Research, said the study found when one of the group used their mobile phone, their companions were more likely to follow shortly after. Overall, the students used their phone on average a quarter of the intervals but, significantly, this increased to almost 40 per cent when their companion had just used their device during the pervious 10-second interval. "There is thus is a pattern of contagion or imitation," he said, adding that this was generally repeated several times. We conducted this study as part of efforts to revitalise Human Ethology, or the observational study of real life behaviour. Some of this could be people being primed to check their e-mail or phone messages, but this contagious use was happening several times in a 15-minute interaction. Dr Kruger believes this pattern could be related to the effects of "social inclusion and exclusion." He added: "If one person in a pair engages in an external conversation through their phone, his or her companion may feel excluded. That companion then might be compelled to connect with others externally so as not to feel left out. An official study, published by Ofcom last year, found British consumers spend more on internet shopping and use smartphones to access the web the most out of any major world economy. The International Communications Market Report, published by the media regulator, found almost two in three 18- to 24-year-olds and 40 per cent of all UK adults use their mobile phones to visit social.