The invention relates to a user interaction device (200, 300) comprising an optical module (210, 310) having a layer (5) of a substance being electrically switchable between a first visual state and a second visual state, and an electrical switch (6a, 6b) for electrically switching the substance between the first and second visual states, a detector (6a, 11b) for detecting the presence of a physical object, and a control unit (290, 390) for controlling the electrical switch in response to the detection of presence of the physical object.