There are no advertisements on this application and all data is kept private, stored only on the iPhone. It works with or without a network connection.
The iPhone is not meant to take the place of therapy, said Herzfeld, but for the "ordinary person" it can act as a "diary of feelings" where they can track their behavioral responses to different emotional states such as drinking, binge eating or overworking.
"Obviously people with serious, difficult breakdowns in their lives need to seek outside help," she said.
Herzfeld's next project is a global awareness project on 1-1-11 -- Jan. 1, 2011. "We Are One" asks people around the world to go online and tell what they are feeling. A Google map will display the responses.