Technological developments and advancements are imminent, where the human user still remains in the center as the end consumer, where having a better understating of natural human reactions, cannot be avoided in order to better enhance such services. Hence, Letos suggests a complementary sensor solution (to vision and voice) that can evaluate true spontaneous physiological reactions as they occur in our utmost natural surroundings - at home, at the office, or when we commute on the road.