Abstract: The invention comprises a mobile device controlled by moving it, for example, by tilting. The mobile device is equipped with wide-angle optics and with a radiation sensor detecting either visible light or infrared radiation. The wide-angle optics may be directed towards the user, whereupon the radiation sensor receives useful images through the wide-angle optics. The images include contrast or thermal differences which it make possible to determine in which way the user has moved the mobile device. In more detail, a tilt angle or a corresponding change can be calculated and then, on the basis of the change, the content shown on a display of the mobile device is altered. The content is, for example, a menu or a web page.