Your smartphone knows more about you than you do - study

Does your smartphone know more about you than you do? Photo / Thinkstock

Mobile phones are the modern person's most faithful companion. They follow us from home to work, the gym and supermarket, and back again.

They never forget a birthday, anniversary or rugby game. And they are always available to offer advice about our finances, spelling and love life.

Your smartphone knows more about you than you do.

A growing number of scientists are starting to mine this data in the hope that it will help them understand what makes us happy or sad, and pinpoint signs of a disease long before it can be diagnosed by a blood sample or MRI.

In one study, researchers at Northwestern University Feinberg School of Medicine in Chicago believe they have found a way for a smartphone to determine if its owner is depressed.

The research team recruited 28 volunteers - 20 females and eight males ranging in age from 19 to 58 - and collected GPS and phone usage information on them for two weeks. The researchers also asked the volunteers to complete health questionnaires. It turned out exactly half had some signs of depression.

In a study published this week in the Journal of Medical Research, they report that the more time people spent using a phone the more likely it was that they were depressed.

But that link didn't hold true for everyone. A second analysis that looked at how people move through time and space showed stronger correlations.

By using this data the researchers were able to identify people with depressive symptoms with 87 per cent accuracy.

"If these methods are successful in finding out if someone has depression ... we'll be able to passively and objectively measure behaviour without a patient having to report this every day," lead author Sohrob Saeb, a computer scientist, said.

Saeb and his colleagues found that three ways a person moves can indicate the presence and severity of depressive symptoms.

They were defined as "circadian movement", "normalised entropy" and "location variance".

Saeb defined circadian movement as how regularly people moved between locations from day to day - "if they move from home to work at the same time across days or at different times," he explained.

They assigned scores based on how "regular" their movements were. The highest score would go to someone who went to the same place at the same time every day.

Although no one in the study scored maximum points, the higher the score, the less likely a person was to have depressive symptoms.

Normalised entropy is a measure of how uniformly people distribute their time between locations. Someone who always stayed in the same place would score zero.

"At the other end you are spending time equally in different locations," Saeb explained.

The higher the score, the less likely a person was to have depressive symptoms.

The last measure, location variance, Saeb defined as "how much you are moving". Again, the higher the number, the fewer the depressive symptoms.

Saeb said the researchers' next step would be to try to duplicate the study in a larger population and to add more sensors so they could measure the types of physical activity, sleep, communications, and other aspects of a person's life.

One promising area, he believes, is in looking at speech patterns and what they can tell about your mental health.