Mobile phone data has been used to accurately predict personality traits.

Smartphones can track who a person talks to, what music they enjoy, and even whether someone is a morning person or a night owl.

Now, new research shows that same information can be used to predict personality types.

A US study recruited 624 volunteers and gathered more than 25 million smartphone datalogging events over 30 days.

The researchers found communication data can be used to predict the personality traits of openness,  conscientiousness,  and extraversion.

However, the data did not shed much light on someone's agreeableness.

The study authors say that as many companies already collect this type of data, it is possible that private personality information is already being gathered without being deliberately provided or explicitly requested.

The study is accessible here.