To make this app working, Emotional sensor is required. Without it, there app has no use. You can buy it here: http://www.happy-electronics.eu/shop/en/home/12-skin-response-biofeedback-for-pc.html The sensor is to connect to your mobile device with Android OS via its microphone input. It measures skin conductance; the measured data are evaluated by this app. Thanks to the app, it's possible to observe behaviour of humans body in stress-situations. The emotional reaction of the body on various stimuli reveal itself as a change in skin conductance that is recorded by the app. The user is offered an opportunity to observe and manage his emotions. The sensor is fixed on index and middle finger, the device is easy to use. The method was scientifically tested and it can be used in various situations to various purposes - by both professional therapists and every who want to learn self-control. It works, for example, as a simple detector of lie.