Scientists are creating a smart phone capable of knowing when people are depressed, and prompting them to seek help.

Researchers at Northwestern University are developing the Mobilyze! device to give depression sufferers more immediate assistance.

In a statement, psychologist and lead researcher David Mohr said the phone would prompt people to speak to friends, reinforcing positive feedback loops.

By prompting people to increase behaviors that are pleasurable or rewarding, we believe that Mobilyze! will improve mood, said Mohr.

It creates a positive feedback loop. Someone is encouraged to see friends, then enjoys himself and wants to do it again. Ruminating alone at home has the opposite effect and causes a downward spiral.

The Mobilyze! device works by using the phone's sensors to record daily habits such as regular walking patterns, physical activity and how many calls or emails the person gets, creating a normal pattern of behavior.

When the user breaks this daily pattern and starts to isolate themselves, the phone automatically suggests they call or see friends.

Small scale trials of the Mobilyze! device have already proved effective in preventing depression.

Mohr added the university was also working on other mental health monitoring technologies.

 The potential to reduce or even prevent depression is enormous, he added.

 These new approaches could offer fundamentally new treatment options to people who are unable to access traditional services or who are uncomfortable with standard psychotherapy. They also can be offered at significantly lower costs, which make them more viable in an era of limited resources.