Researchers from University of Pennsylvania in the US used character assessment software to analyse the profile pictures of 66,000 Twitter users, and asked a further 434 people to fill in a psychological survey.

They sorted the respondents into five personality categories - neuroticism, agreeableness, conscientiousness, extroversion and openness to experience, 'The Telegraph' reported.

According to researchers, neurotic people have trouble holding back their negative emotions. Participants in this category are likely to set their profile picture as something other than their face, such as a pet or building, they said. Users who are agreeable are the most likely to be cheerful, get along with others and smile, researchers said. The profile pictures of agreeable people are one of the most likely to be colourful, and will feature the person laughing, playing with others or smiling broadly, they said.

Conscientious people are those who enjoy "orderliness, planned behaviour and self-discipline," researchers said. They are more likely to appear older than their years in profile pictures, and will use techniques such as wearing glasses or smarter clothes to achieve this, they said.

Like agreeable people, even extroverts are likely to have colourful profile pictures and are always smiling. They also tend to pose with young people, or adopt other techniques to make themselves appear younger than they are, researchers said.

People who are open to experience are those who enjoy tackling new, exciting experiences and are not afraid to pose in an odd way. They are most likely to pose with an object and take colourless photos, looking angry or sad, researchers said.