Psychologists at Swansea University and Milan University studied personality changes in 74 people aged 18 to 34.
They also assessed participants’ use of social media over a four-month period.
The researchers found “problematic” use of visual forms of social media, such as posting selfies, “appears to drive levels of narcissism” in a way that primarily textual usage does not.
Internet usage is defined as problematic when there are multiple negative impacts on an individual’s life, such as withdrawal effects when disconnected and interference with friendships.
All but one of the study’s participants used social media, with their average usage – excluding for work – about three hours a day.
Some reported using social media for as much as eight hours a day for non-work related purposes.
Facebook was used by 60 per cent of participants, while a quarter used Instagram and 13 per cent used Twitter and Snapchat each.
More than two-thirds of the participants primarily used social media for posting images.
Over the four months, the increase in narcissistic traits took many of the participants above the clinical cut-off for Narcissistic Personality Disorder.
Narcissism is a personality characteristic that can involve grandiose exhibitionism, a sense of entitlement, and exploiting others.
Professor Phil Reed, of the Department of Psychology at Swansea University, said: “There have been suggestions of links between narcissism and the use of visual postings on social media, such as Facebook, but, until this study, it was not known if narcissists use this form of social media more, or whether using such platforms is associated with the subsequent growth in narcissism.
“The results of this study suggest that both occur, but show that posting selfies can increase narcissism.
“Taking our sample as representative of the population, which there is no reason to doubt, this means that about 20 per cent of people may be at risk of developing such narcissistic traits associated with their excessive visual social media use.
“That the predominant usage of social media for the participants was visual, mainly through Facebook, suggests the growth of this personality problem could be seen increasingly more often, unless we recognise the dangers in this form of communication.”
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