Facebook ad campaigns created by British and US researchers have targeted millions of people based on a single 'like'.
Scientists used whether people liked certain pages to figure out their personality type, showing the effect of 'mass psychological persuasion', the researchers said.
The study reveals that even the smallest 'digital footprint' can be used to influence the behaviour of large groups of people.
Scroll down for video
Facebook ad campaigns created by British and US researchers have targeted millions of people based on a single 'like'. Each person's Facebook 'like' was used to figure out their psychological traits, showing the effect of 'mass psychological persuasion' (stock image)
For the research, experts used a database that linked millions of personality profiles of anonymous Facebook users with their 'likes'.
The data showed that specific personality traits are more likely among those that like certain pages.
For example, someone who likes Lady Gaga's Facebook page is more likely to be confident and outspoken, or 'extroverted'.
A like for the Sci-Fi television series Stargate means someone is more likely to be shy and reserved, or 'introverted'.
The team then had graphic designers create adverts for people that are either extroverts or introverts.
They showed these adverts to people based on a single 'like' linked to their page that suggested they were either an introvert or extrovert.
The researchers, from Cambridge University and New York's Colombia Business School (CBS), ran fake ad campaigns after realising it was possible to guess whether someone was outgoing or shy based on a single Facebook like.
'Whether you like it or not, almost every step you take online is recorded: The websites you visit, the purchases you make, the songs you listen to, the messages you post or read on social sites, and the pages you follow on Facebook,' lead researcher Dr Sandra Matz, from CBS, wrote in a press release.
'These digital footprints provide a treasure trove of data that can reveal not only what you like and how you see the world, but also who you are as a person.'
The US and British team targeted 3.5 million people with their fake advertising campaigns.
Ads were aimed mostly at women in the UK aged 18-40, and were tailored to their personality type based on a single Facebook like.
The team found that their campaigns, which they ran for a number of unnamed companies, boosted clicks on ads for Beauty products and gaming apps by up to 40 per cent compared with untargeted adverts.
Sales for these products were hiked by as much as 50 per cent compared with untargeted campaigns.
'Our research shows that digital footprints can be used to influence effectively the behaviour of large groups of people,' Dr Matz wrote.
'By targeting consumers with persuasive messages that are tailored to their core psychological profiles (e.g. the degree to which they are extroverted or introverted) it is possible to significantly increase the