The idea is that people being treated for depression will have the technology running on their phones. As they go about their lives, the app will always be paying attention. When the app detects that a user is severely depressed -- say, because he or she stayed in bed all day or hasn't been physically active -- it would automatically contact a healthcare professional working with the patient.

The technology is also being tested for use with average, healthy users. Ideally, it could provide a lot if information about whether someone is happy or sad, depressed or anxious -- in short, it could constantly detect mood and emotion.

Researchers at are using entirely different data to detect the emotions of smartphone users.

Samsung's method is to , such as how fast the user types, how much the backspace button is used and even how much the phone is shaking during use to figure out if the user is happy, angry, fearful, sad or disgusted.

In fact, there are many ways to use the sensors in smartphones to detect people's moods or emotions.